Congenital Uterine Malformation by Experts (CUME): diagnostic criteria for T-shaped uterus.

OBJECTIVES: To identify uterine measurements that are reliable and accurate to distinguish between T-shaped and normal/arcuate uterus, and define T-shaped uterus, using Congenital Uterine Malformation by Experts (CUME) methodology, which uses as reference standard the decision made most often by several independent experts. METHODS: This was a prospectively planned multirater reliability/agreement and diagnostic accuracy study, performed between November 2017 and December 2018, using a sample of 100 three-dimensional (3D) datasets of different uteri with lateral uterine cavity indentations, acquired from consecutive women between 2014 and 2016. Fifteen representative experts (five clinicians, five surgeons and five sonologists), blinded to each others' opinions, examined anonymized images of the coronal plane of each uterus and provided their independent opinion as to whether it was T-shaped or normal/arcuate; this formed the basis of the CUME reference standard, with the decision made most often (i.e. that chosen by eight or more of the 15 experts) for each uterus being considered the correct diagnosis for that uterus. Two other experienced observers, also blinded to the opinions of the other experts, then performed independently 15 sonographic measurements, using the original 3D datasets of each uterus. Agreement between the diagnoses made by the 15 experts was assessed using kappa and percent agreement. The interobserver reliability of measurements was assessed using the concordance correlation coefficient (CCC). The diagnostic test accuracy was assessed using the area under the receiver-operating-characteristics curve (AUC) and the best cut-off value was assessed by calculating Youden's index, according to the CUME reference standard. Sensitivity, specificity, negative and positive likelihood ratios (LR- and LR+) and post-test probability were calculated. RESULTS: According to the CUME reference standard, there were 20 T-shaped and 80 normal/arcuate uteri. Individual experts recognized between 5 and 35 (median, 19) T-shaped uteri on subjective judgment. The agreement among experts was 82% (kappa = 0.43). Three of the 15 sonographic measurements were identified as having good diagnostic test accuracy, according to the CUME reference standard: lateral indentation angle (AUC = 0.95), lateral internal indentation depth (AUC = 0.92) and T-angle (AUC = 0.87). Of these, T-angle had the best interobserver reproducibility (CCC = 0.87 vs 0.82 vs 0.62 for T-angle vs lateral indentation depth vs lateral indentation angle). The best cut-off values for these measurements were: lateral indentation angle ≤ 130° (sensitivity, 80%; specificity, 96%; LR+, 21.3; LR-, 0.21), lateral indentation depth ≥ 7 mm (sensitivity, 95%; specificity, 77.5%; LR+, 4.2; LR-, 0.06) and T-angle ≤ 40° (sensitivity, 80%; specificity, 87.5%; LR+, 6.4; LR-, 0.23). Most of the experts diagnosed the uterus as being T-shaped in 0% (0/56) of cases when none of these three criteria was met, in 10% (2/20) of cases when only one criterion was met, in 50% (5/10) of cases when two of the three criteria were met, and in 93% (13/14) of cases when all three criteria were met. CONCLUSIONS: The diagnosis of T-shaped uterus is not easy; the agreement among experts was only moderate and the judgement of individual experts was commonly insufficient for accurate diagnosis. The three sonographic measurements with cut-offs that we identified (lateral internal indentation depth ≥ 7 mm, lateral indentation angle ≤ 130° and T-angle ≤ 40°) had good diagnostic test accuracy and fair-to-moderate reliability and, when applied in combination, they provided high post-test probability for T-shaped uterus. In the absence of other anomalies, we suggest considering a uterus to be normal when none or only one criterion is met, borderline when two criteria are met, and T-shaped when all three criteria are met. These three CUME criteria for defining T-shaped uterus may aid in determination of its prevalence, clinical implications and best management and in the assessment of post-surgical morphologic outcome. The CUME definition of T-shaped uterus may help in the development of interventional randomized controlled trials and observational studies and in the diagnosis of uterine morphology in everyday practice, and could be adopted by guidelines on uterine anomalies to enrich their classification systems. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnosis and management of patients with enhanced myometrial vascularity associated with retained products of conception.

OBJECTIVES: To assess the complication rate, including estimated amount of blood loss, in patients undergoing dilation and curettage (D&C) for the treatment of retained products of conception with markedly enhanced myometrial vascularity mimicking arteriovenous malformation. METHODS: This was a retrospective medical-records review study of patients with retained products of conception with enhanced myometrial vascularity presenting to our ultrasound unit between August 2015 and August 2017. Color/power Doppler imaging was used subjectively to identify the degree and extent of vascularity. All patients underwent D&C, and their operative reports and medical records were reviewed to see if ultrasound guidance was used, to ascertain estimated blood loss and to identify complications during or after the procedure. RESULTS: The study group included 31 patients, of whom seven had retained products of conception after a vaginal delivery and 24 had retained products of conception after a first-trimester termination or miscarriage. The largest dimension of the region of enhanced myometrial vascularity ranged from 10 mm to 53 mm, with 14/31 having a width of ≥ 20 mm. Fifteen patients underwent a standard D&C procedure, 13 an ultrasound-guided procedure and three hysteroscopy. Estimated operative blood loss varied from negligible to a maximum of 400 mL. There were no intraoperative complications, although one patient was treated for presumed endometritis. CONCLUSIONS: An increasing number of studies describe the enhanced myometrial vascularity associated with retained products of conception as 'acquired arteriovenous malformation', with some recommending management with uterine-artery embolization. Our study demonstrates that the enhanced myometrial vascularity is associated with retained products of conception, and surgical removal by D&C, possibly with the aid of ultrasound guidance or hysteroscopy, is a safe treatment option. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Obstetric and gynecologic ultrasound curriculum and competency assessment in residency training programs: consensus report.

Ultrasound imaging has become integral to the practice of obstetrics and gynecology. With increasing educational demands and limited hours in residency programs, dedicated time for training and achieving competency in ultrasound has diminished substantially. The American Institute of Ultrasound in Medicine assembled a multi-Society Task Force to develop a consensus-based, standardized curriculum and competency assessment tools for obstetric and gynecologic ultrasound training in residency programs. The curriculum and competency-assessment tools were developed based on existing national and international guidelines for the performance of obstetric and gynecologic ultrasound examinations and thus are intended to represent the minimum requirement for such training. By expert consensus, the curriculum was developed for each year of training, criteria for each competency assessment image were generated, the pass score was established at or close to 75% for each, and obtaining a set of five ultrasound images with pass score in each was deemed necessary for attaining each competency. Given the current lack of substantial data on competency assessment in ultrasound training, the Task Force expects that the criteria set forth in this document will evolve with time. The Task Force also encourages use of ultrasound simulation in residency training and expects that simulation will play a significant part in the curriculum and the competency-assessment process. Incorporating this training curriculum and the competency-assessment tools may promote consistency in training and competency assessment, thus enhancing the performance and diagnostic accuracy of ultrasound examination in obstetrics and gynecology. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Counting ovarian antral follicles by ultrasound: a practical guide.

This Consensus Opinion summarizes the main aspects of several techniques for performing ovarian antral follicle count (AFC), proposes a standardized report and provides recommendations for future research. AFC should be performed using a transvaginal ultrasound (US) probe with frequency ≥ 7 MHz. For training, we suggest a minimum of 20-40 supervised examinations. The operator should be able to adjust the machine settings in order to achieve the best contrast between follicular fluid and ovarian stroma. AFC may be evaluated using real-time two-dimensional (2D) US, stored 2D-US cine-loops and stored three-dimensional (3D) US datasets. Real-time 2D-US has the advantage of permitting additional maneuvers to determine whether an anechoic structure is a follicle, but may require a longer scanning time, particularly when there is a large number of follicles, resulting in more discomfort to the patient. 2D-US cine-loops have the advantages of reduced scanning time and the possibility for other observers to perform the count. The 3D-US technique requires US machines with 3D capability and the operators to receive additional training for acquisition/analysis, but has the same advantages as cine-loop and also allows application of different imaging techniques, such as volume contrast imaging, inversion mode and semi-automated techniques such as sonography-based automated volume calculation. In this Consensus Opinion, we make certain recommendations based on the available evidence. However, there is no strong evidence that any one method is better than another; the operator should choose the best method for counting ovarian follicles based on availability of resources and on their own preference and skill. More studies evaluating how to improve the reliability of AFC should be encouraged. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

International Endometrial Tumor Analysis (IETA) terminology in women with postmenopausal bleeding and sonographic endometrial thickness ≥ 4.5 mm: agreement and reliability study.

OBJECTIVE: To estimate intra- and interrater agreement and reliability with regard to describing ultrasound images of the endometrium using the International Endometrial Tumor Analysis (IETA) terminology. METHODS: Four expert and four non-expert raters assessed videoclips of transvaginal ultrasound examinations of the endometrium obtained from 99 women with postmenopausal bleeding and sonographic endometrial thickness ≥ 4.5 mm but without fluid in the uterine cavity. The following features were rated: endometrial echogenicity, endometrial midline, bright edge, endometrial-myometrial junction, color score, vascular pattern, irregularly branching vessels and color splashes. The color content of the endometrial scan was estimated using a visual analog scale graded from 0 to 100. To estimate intrarater agreement and reliability, the same videoclips were assessed twice with a minimum of 2 months' interval. The raters were blinded to their own results and to those of the other raters. RESULTS: Interrater differences in the described prevalence of most IETA variables were substantial, and some variable categories were observed rarely. Specific agreement was poor for variables with many categories. For binary variables, specific agreement was better for absence than for presence of a category. For variables with more than two outcome categories, specific agreement for expert and non-expert raters was best for not-defined endometrial midline (93% and 96%), regular endometrial-myometrial junction (72% and 70%) and three-layer endometrial pattern (67% and 56%). The grayscale ultrasound variable with the best reliability was uniform vs non-uniform echogenicity (multirater kappa (κ), 0.55 for expert and 0.52 for non-expert raters), and the variables with the lowest reliability were appearance of the endometrial-myometrial junction (κ, 0.25 and 0.16) and the nine-category endometrial echogenicity variable (κ, 0.29 and 0.28). The most reliable color Doppler variable was color score (mean weighted κ, 0.77 and 0.69). Intra- and interrater agreement and reliability were similar for experts and non-experts. CONCLUSIONS: Inter- and intrarater agreement and reliability when using IETA terminology were limited. This may have implications when assessing the association between a particular ultrasound feature and a specific histological diagnosis, because lack of reproducibility reduces the reliability of the association between a feature and the outcome. Future studies should investigate whether using fewer categories of variable or offering practical training could improve agreement and reliability. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Congenital Uterine Malformation by Experts (CUME): better criteria for distinguishing between normal/arcuate and septate uterus?

OBJECTIVES: To assess the level of agreement between experts in distinguishing between septate and normal/arcuate uterus using their subjective judgment when reviewing the coronal view of the uterus from three-dimensional ultrasound. Another aim was to determine the interobserver reliability and diagnostic test accuracy of three measurements suggested by recent guidelines, using as reference standard the decision made most often by experts (Congenital Uterine Malformation by Experts (CUME)). METHODS: Images of the coronal plane of the uterus from 100 women with suspected fundal internal indentation were anonymized and provided to 15 experts (five clinicians, five surgeons and five sonologists). They were instructed to indicate whether they believed the uterus to be normal/arcuate (defined as normal uterine morphology or not clinically relevant degree of distortion caused by internal indentation) or septate (clinically relevant degree of distortion caused by internal indentation). Two other observers independently measured indentation depth, indentation angle and indentation-to-wall-thickness (I:WT) ratio. The agreement between experts was assessed using kappa, the interobserver reliability was assessed using the concordance correlation coefficient (CCC), the diagnostic test accuracy was assessed using the area under the receiver-operating characteristics curve (AUC) and the best cut-off value was assessed using Youden's index, considering as the reference standard the choice made most often by the experts (CUME). RESULTS: There was good agreement between all experts (kappa, 0.62). There were 18 septate and 82 normal/arcuate uteri according to CUME; European Society of Human Reproduction and Embryology (ESHRE)-European Society for Gynaecological Endoscopy (ESGE) criteria (I:WT ratio > 50%) defined 80 septate and 20 normal/arcuate uteri, while American Society for Reproductive Medicine (ASRM) criteria defined five septate (depth > 15 mm and angle < 90°), 82 normal/arcuate (depth < 10 mm and angle > 90°) and 13 uteri that could not be classified (referred to as the gray-zone). The agreement between ESHRE-ESGE and CUME was 38% (kappa, 0.1); the agreement between ASRM criteria and CUME for septate was 87% (kappa, 0.39), and considering both septate and gray-zone as septate, the agreement was 98% (kappa, 0.93). Among the three measurements, the interobserver reproducibility of indentation depth (CCC, 0.99; 95% CI, 0.98-0.99) was better than both indentation angle (CCC, 0.96; 95% CI, 0.94-0.97) and I:WT ratio (CCC, 0.92; 95% CI, 0.90-0.94). The diagnostic test accuracy of these three measurements using CUME as reference standard was very good, with AUC between 0.96 and 1.00. The best cut-off values for these measurements to define septate uterus were: indentation depth ≥ 10 mm, indentation angle < 140° and I:WT ratio > 110% . CONCLUSIONS: The suggested ESHRE-ESGE cut-off value overestimates the prevalence of septate uterus while that of ASRM underestimates this prevalence, leaving in the gray-zone most of the uteri that experts considered as septate. We recommend considering indentation depth ≥ 10 mm as septate, since the measurement is simple and reliable and this criterion is in agreement with expert opinion. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Systematic approach to sonographic evaluation of the pelvis in women with suspected endometriosis, including terms, definitions and measurements: a consensus opinion from the International Deep Endometriosis Analysis (IDEA) group.

The IDEA (International Deep Endometriosis Analysis group) statement is a consensus opinion on terms, definitions and measurements that may be used to describe the sonographic features of the different phenotypes of endometriosis. Currently, it is difficult to compare results between published studies because authors use different terms when describing the same structures and anatomical locations. We hope that the terms and definitions suggested herein will be adopted in centers around the world. This would result in consistent use of nomenclature when describing the ultrasound location and extent of endometriosis. We believe that the standardization of terminology will allow meaningful comparisons between future studies in women with an ultrasound diagnosis of endometriosis and should facilitate multicenter research. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Nuchal Translucency Quality Review (NTQR) program: first one and half million results.

OBJECTIVE: To evaluate the performance of first-trimester nuchal translucency (NT) measurement by providers (physician-sonologists and sonographers) within the Nuchal Translucency Quality Review (NTQR) program. METHODS: After training and credentialing providers, the NTQR monitored performance of NT measurement by the extent to which an individual's median multiple of the normal median (MoM) for crown-rump length (CRL) was within the range 0.9-1.1 MoM of a published normal median curve. The SD of log10 MoM and regression slope of NT on CRL were also evaluated. We report the distribution between providers of these performance indicators and evaluate potential sources of variation. RESULTS: Among the first 1.5 million scans in the NTQR program, performed between 2005 and 2011, there were 1 485 944 with CRL in the range 41-84 mm, from 4710 providers at 2150 ultrasound units. Among the 3463 providers with at least 30 scans in total, the median of the providers' median NT-MoMs was 0.913. Only 1901 (55%) had a median NT-MoM within the expected range; there were 89 above 1.1 MoM, 1046 at 0.8-0.9 MoM, 344 at 0.7-0.8 MoM and 83 below 0.7 MoM. There was a small increase in the median NT-MoM according to providers' length of time in the NTQR program and number of scans entered annually. On average, physician-sonologists had a higher median NT-MoM than did sonographers, as did those already credentialed before joining the program. The median provider SD was 0.093 and the median slope was 13.5%. SD correlated negatively with the median NT-MoM (r = -0.34) and positively with the slope (r = 0.22). CONCLUSION: Even with extensive training, credentialing and monitoring, there remains considerable variability between NT providers. There was a general tendency towards under-measurement of NT compared with expected values, although more experienced providers had performance closer to that expected.

Terms, definitions and measurements to describe sonographic features of myometrium and uterine masses: a consensus opinion from the Morphological Uterus Sonographic Assessment (MUSA) group.

The MUSA (Morphological Uterus Sonographic Assessment) statement is a consensus statement on terms, definitions and measurements that may be used to describe and report the sonographic features of the myometrium using gray-scale sonography, color/power Doppler and three-dimensional ultrasound imaging. The terms and definitions described may form the basis for prospective studies to predict the risk of different myometrial pathologies, based on their ultrasound appearance, and thus should be relevant for the clinician in daily practice and for clinical research. The sonographic features and use of terminology for describing the two most common myometrial lesions (fibroids and adenomyosis) and uterine smooth muscle tumors are presented.

Imaging in gynecological disease. 10: Clinical and ultrasound characteristics of decidualized endometriomas surgically removed during pregnancy.

OBJECTIVES: To describe the clinical history and ultrasound findings in women with decidualized endometriomas surgically removed during pregnancy. METHODS: In this retrospective study, women with a histological diagnosis of decidualized endometrioma during pregnancy who had undergone preoperative ultrasound examination were identified from the databases of seven ultrasound centers. The ultrasound appearance of the tumors was described on the basis of ultrasound images, ultrasound reports and research protocols (when applicable) by one author from each center using the terms and definitions of the International Ovarian Tumor Analysis (IOTA) group. In addition, two authors reviewed together available digital ultrasound images and used pattern recognition to describe the typical ultrasound appearance of decidualized endometriomas. RESULTS: Eighteen eligible women were identified. Median age was 34 (range, 20-43) years. Median gestational age at surgical removal of the decidualized endometrioma was 18 (range, 11-41) weeks. Seventeen women (94%) were asymptomatic and one presented with pelvic pain. In three of the 18 women an ultrasound diagnosis of endometrioma had been made before pregnancy. The original ultrasound examiner was uncertain whether the mass was benign or malignant in 10 (56%) women and suggested a diagnosis of benignity in nine (50%) women, borderline in eight women (44%), and invasive malignancy in one (6%) woman. Seventeen decidualized endometriomas contained a papillary projection, and in 16 of these at least one of the papillary projections was vascularized at power or color Doppler examination. The number of cyst locules varied between one (n = 11) and four. No woman had ascites. When using pattern recognition, most decidualized endometriomas (14/17, 82%) were described as manifesting vascularized rounded papillary projections with a smooth contour in an ovarian cyst with one or a few cyst locules and ground-glass or low-level echogenicity of the cyst fluid. CONCLUSIONS: Rounded vascularized papillary projections with smooth contours within an ovarian cyst with cyst contents of ground-glass or low-level echogenicity are typical of surgically removed decidualized endometriomas in pregnant women, most of whom are asymptomatic.

The role of Ia molecules in the activation of T lymphocytes. III. Antigen-specific, Ia-restricted, interleukin 2-producing T cell hybridomas with detectable affinity for the restricting I-A molecule.

Antigen-specific I region-restricted, interleukin 2-producing T cell hybridomas were produced by fusing GAT-specific T cell blasts with BW5147. Two antigen-specific phenotypes were identified, one autoreactive and one nonautoreactive. All of the antigen-specific and autoreactive clones were H-2 restricted, mapping to the IA subregion by genetic analysis and monoclonal antibody inhibition. Both the antigen-specific and autoreactive stimulation are the property of a single cell and required no known exogenous antigens.

Antihapten antibody specificity and L chain type.

Two types of light polypeptide chain (kappa and lambda) are present in guinea pig immunoglobulins. The ratios of K/L molecules in anti-hapten antibodies differ sometimes markedly from that found in normal serum. Anti-DNP antibodies and anti-pipsyl antibodies have, respectively, a higher and a lower than normal K/L ratio. The possibility that the L chain type affects the range of configurations which the antibody-combining site may assume was investigated. Fractional precipitation of anti-DNP antibodies from serum of guinea pigs immunized with DNP(44)-BSA was performed using limiting amounts of antigen. Antibody fractions were purified from each precipitate, their affinities for epsilon-DNP-L-lysine measured by fluorescence quenching (K(0)) and the K/L ratio estimated by precipitation with specific antisera. Increasing concentrations of L molecules were found in fractions with decreasing K(0). In other experiments, fractional precipitation and purification of antibodies which cross-react with DNP was performed in serum of animals immunized with pipsyl-BGG. The K/L ratio in antibodies isolated from these fractions was much higher than in fractions which do not cross-react with DNP. These results show that K molecules are better adapted to react with the DNP hapten than L molecules. The K/L ratio in anti-DNP antibody was shown to increase in the course of immunization, at the same time that the K(0) is increasing. This rise in K(0) is markedly delayed when larger doses of antigen are employed.

Quantitative variations in L chain types in guinea pig antihapten antibodies.

In guinea pig purified antihapten antibodies, the proportion of molecules bearing the kappa- or lambda-type of L chains (K or L molecules) may diverge markedly from that found in normal gamma(2)-globulins. This has been evaluated by precipitation of I(131)-labeled antibody preparations using a specific anti-lambda-chain antiserum. Anti-DNP antibodies isolated 3 wk after immunization of guinea pigs with DNP(65)-BGG antibodies, contain less than 1% of L molecules, while in pipsyl antibodies, isolated from the sera of animals immunized with pipsyl-BGG, the proportion of L molecules is significantly greater than in normal gamma(2)-globulins. Anti-DNP antibodies produced against conjugates of this hapten with carriers other than BGG (BSA, OVA, or poly-L-lysine) or with BGG with a small number of DNP groups (DNP(10)-BGG) contained a greater proportion of lambda-chain bearing molecules than anti-DNP antibodies isolated from late sera of guinea pigs immunized with highly conjugated DNP(65)-BGG. An increased percentage of L molecules was detected in preparations of anti-DNP(65)-BGG antibodies isolated early (10 days), when compared to those isolated later during the course of immunization. However, the level of L molecules in all these anti-DNP antibody preparations was always considerably below that present in normal gamma(2)-globulin. The relative amounts of L molecules in distinct immunoglobulin families (gamma(1) and gamma(2)) in antibody preparations isolated from individual animals was remarkably similar.

Properties of antibodies cytophilic for macrophages.

Cytophilic activity for macrophages was shown to be a property possessed by most, if not all, of the complement binding 7S gamma(2)-population of guinea pig antibodies. Cytophilic antibodies were also demonstrated in rabbit and mouse antisera to sheep red cells. While each species antibody best sensitized homologous macrophages, cross species sensitization was also observed. The binding site for macrophages resides on the Fc fragment, therefore, on the H chains, and is destroyed by pepsin hydrolysis or reduction and alkylation. The binding reaction is reversible with a high rate of dissociation at 37 degrees C. Cytophilic activity is not complement dependent, and was shown to be that property of opsonizing antibody which provides the receptors that permit the binding of the antibody to the macrophage cell membrane in preparation for phagocytosis.

The involvement of suppressor T cells in Ir gene regulation of secondary antibody responses of primed (responder X nonresponder)F1 mice to macrophage-bound L-glutamic acid60-L-alanine30-L-tyrosine.

(Responder [R] X nonresponder [NR])F1 mice give indistinguishable primary in vitro plaque-forming cell (PFC) responses to either R or NR parental macrophages (Mphi) pulsed with the Ir-gene controlled antigen L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT). However, such (R X NR)F1 mice, if primed to GAT, retained in vitro responsiveness to GAT-R-Mphi, but no longer responded to GAT-NR-Mphi. This suggested (a) a possible Mphi-related locus for Ir gene activity in this model, and (b) the occurrence of active suppression after priming with GAT leading to a selective loss of the usual primary responsiveness of (R X NR)F1 mice to GAT-NR-Mphi. This latter interpretation was tested in the current study. [Responder C57BL/6 (H-2b) X nonresponder DBA/1 (H-2q)]F1 mice were primed with 100 microgram GAT in pertussis adjuvant. 4-8 wk later, spleen cells from such mice were tested alone or mixed with normal unprimed F1 spleen cells for PFC responses to GAT-R-Mphi and GAT-NR-Mphi. The primed cells failed to respond to GAT-NR-Mphi, and moreover, actively suppressed the normal response of unprimed F1 cells to GAT-NR-Mphi. If the primed spleen cell donor had been treated with 5 mg/kg cyclophosphamide 3 days before priming or with 5-10 microliter/day of an antiserum to the I-Jb subregion [B10.A(5R) anti B10.A(3R)] during the first 4 days postpriming (both procedures known to inhibit suppressor T-cell activity), cells from such mice responded in secondary culture to both GAT-R-Mphi and also GAT-NR-MPhi. In addition, such spleen cells no longer were capable of suppressing normal F1 cells in response to GAT-NR-Mphi. Similar data were obtained using [CBA (H-2k) X DBA/1 (H-2q)]F1. Further, it was shown that (a) primary responsiveness to GAT-NR-Mphi was not an artifact of in vitro Mphi pulsing, because in vivo GAT-pulsed Mphi showed the same activity and (b) the secondary restriction for Mphi-antigen presentation was controlled by H-2 linked genes. These data suggest an important role for suppressor T cells in H-2 restricted secondary PFC responses, and also provide additional support for the hypothesis that Ir-gene controlled differences in Mphi antigen presentation are related to both suppressor cell generation and overall responsiveness in the GAT model.

Inhibition of antigen-specific T lymphocyte activation by structurally related Ir gene-controlled polymers. II. Competitive inhibition of I-E-restricted, antigen-specific T cell responses.

Our previous studies have defined a highly specific competitive inhibition between a pair of structurally related antigens (GT and GAT) for antigen presentation by accessory cells. The present report investigates this phenomenon in a second antigenic system, which is controlled by a distinct Ir gene product. Two GL phi-specific, I-Ed-restricted, interleukin 2-producing T cell hybridomas were constructed. The antigenic fine specificity of these two hybrid clones was distinct. One hybrid reacted solely with GL phi while the second cross-reacted with GLleu and GLT. These latter two copolymers, as well as the antigen GL, were found to inhibit the GL phi response of the non-cross-reactive hybrid. The structurally related antigen G phi was not inhibitory for this clone's response. The cross-reactive GL phi hybrid could also be inhibited, but, in this case, G phi and not GL caused the inhibition. Reciprocal inhibitions could be demonstrated between these and other hybrids (e.g., GAT responsive), indicating a very high degree of specificity to the inhibition. The inhibition caused by the various copolymers was reversible by increasing the concentration of GL phi, This effect was localized to the antigen-presenting cell and not the T cell hybridoma. Functionally, this competition did not appear to be for antigen uptake or general antigen processing. These findings generalize the phenomenon of antigen competition to a second antigen system in the context of a second Ia molecule. The possible mechanisms accounting for the complex pattern of specificities in this system are discussed.

Selective modification of a private I-A allo-stimulating determinant(s) upon association of antigen with an antigen-presenting cell.

A large panel of alloreactive, interleukin 2 (IL-2)-producing T cell hybridomas was constructed from B10 alpha BALB/c primary mixed lymphocyte cultures (MLC). Functional hybrids had specificity for either I-Ad or I-Ed. These cells were used to probe determinants on Ia molecules in an attempt to detect molecular association between a nominal antigen and an Ia molecule on an antigen-presenting cell (APC). The response of a small number of these clones was significantly blocked by the addition of the Ir gene-controlled copolymer L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) to culture. A comparison of the inhibited and uninhibited hybrids revealed an identical dose response curve. Further, both types of hybrids were activated by the same stimulator cell and frequently recognized the identical Ia molecule on that cell. Nevertheless, the inhibitory effect of GAT was localized to the stimulator cell and not to the T cell hybrids. All of the hybrids whose stimulation was blocked had specificity for the I-A molecule, which is the gene product known to control and restrict responsiveness to GAT. Further, only GT, but not a number of other related antigens, was also specifically inhibitory, which correlates with the known associational specificity of these antigens on an APC. Finally, the same stimulator cell could be shown to coordinately lose an allostimulatory determinant(s), while it was gaining an I-Ad plus GAT determinant(s). The implications of these findings on the nature of antigen-Ia association and on the role of polymorphic Ia determinants are discussed.

Inhibition of antigen-specific T lymphocyte activation by structurally related Ir gene-controlled polymers. Evidence of specific competition for accessory cell antigen presentation.

The interaction of nominal Ag with major histocompatibility complex (MHC)-restricted T cells and accessory cells was studied by analyzing the effect of structurally related antigens on the response of antigen-specific MHC-restricted T cell hybridomas. The copolymer L-glutamic acid50-L-tyrosine50 (GT) completely inhibits the response of L-glutamic acid60-L-alanine40-L-tyrosine10 (GAT)-specific, I-Ad-restricted T cell hybridomas to GAT plus accessory cells. This inhibition is specific, as hybridomas of other specificities are not inhibited under identical conditions, and is unique to the GT antigen, as other similar copolymers are not inhibitory. The inhibitory effect is reversible by adding increasing amounts of GAT. Antigen-pulsing experiments localized the inhibition to the level of antigen-presenting cell (APC). GT-prepulsed APC are not inhibitory in cell-mixing experiments and can present other antigens. GT only inhibits the nominal antigen-directed component of a GAT-specific, autoreactive hybrid's response. Together these findings suggest that GT causes inhibition by competing for GAT association at the accessory cell. GT interferes with GAT presentation by an I-Adxb F1 APC to a BALB/c, I-Ad-restricted, but not B10, I-Ab-restricted, T cell hybridoma, and GT inhibits presentation by GAT-prepulsed APC. The implications of these findings for MHC-restricted presentation of antigen are discussed.