Prognostic value of lymphocyte-to-monocyte ratio and histone methyltransferase G9a histone methyltransferase in patients with double expression lymphoma: A retrospective observational study.

ABSTRACT: In patients with diffuse large B-cell lymphoma, MYC combined with Bcl2 and/or Bcl6-based protein expression is called double expression lymphoma (DEL). R-DA-EPOCH program chemotherapy is typically recommended because these patients often have a poor prognosis. Although numerous factors affect survival of patients with DEL, the roles of the tumor biomarker histone methyltransferase G9a (G9a) and the lymphocyte-to-monocyte ratio (LMR) are unknown.We performed a retrospective analysis of data from 51 patients. These patients were newly diagnosed with DEL and treated with R-DA-EPOCH at Taizhou People' s Hospital and Northern Jiangsu People's Hospital between June 2014 and December 2019. Receiver operator characteristic curve results were used to calculate the LMR cutoff value. We used an immunohistochemical analysis to examine G9a expression in DEL tissues. The Kaplan-Meier method was used to determine progression-free survival (PFS) and overall survival (OS) characteristics. Cox proportional-hazards models were constructed for univariate and multivariate analyses to examine the prognostic values of LMRs and G9a in patients with DEL.The cutoff value for LMR was 2.18. The 5-year PFS rate was 35.3%, and the 5-year OS rate was 39.2%. Patients with DEL with lower LMRs and who were G9a-positive predicted inferior PFS and OS. Univariate analysis revealed that patients with elevated LDH levels, high National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) scores, LMRs ≤2.18, and G9a-positive results had relatively poorer PFS and OS. The multivariate analysis revealed that LMRs ≤2.18 and a G9a-positive result were independent prognostic factors for PFS and OS in patients with DEL treated with R-DA-EPOCH.The study results suggested that peripheral blood LMRs were an important marker for evaluation of prognosis in patients with DEL. High expression of G9a was associated with worse outcomes, indicating that G9a may serve as a prognostic biomarker for patients with DEL who undergo R-DA-EPOCH program chemotherapy.

Serum proteomic changes in adults with obstructive sleep apnoea.

To examine whether differentially expressed proteins are present in the serum of patients with obstructive sleep apnoea (OSA), iTRAQ techniques (isobaric tags for relative and absolute quantification) were employed in a prospective study. Individuals were assigned to either a non-OSA control group (apnoea-hypopnoea index, AHI <5) or an OSA group (AHI ≥5). Blood samples were collected, aliquoted and frozen at -80 °C. Protein digestion and tagging with iTRAQ4plex® and mass spectrometry analysis was then performed (MALDI TOF/TOF). Ten male subjects were included in the control group (age = 45 ± 9.7 years) and 30 male patients in the OSA group (age = 45 ± 10.7 years), the latter being then subdivided into three severity groups. A total of 103 proteins were identified with differential levels between patients with OSA and controls. Of these, 11 proteins were underexpressed and 19 were overexpressed in patients with OSA. C4BPA and thrombospondin were underexpressed in all three OSA severity groups. Among the overexpressed proteins, 13 were overexpressed in the mild OSA group, seven in the moderate group and five in the severe group. Analysis of interactions between the identified proteins revealed that protein alterations in OSA are primarily associated with derangements in lipid and vascular metabolic pathways. This study provides initial evidence that differential protein expression occurs in adults with OSA, and that such proteins change according to disease severity, and appear to primarily involve lipid and vascular metabolic pathways.

Immunity, thyroid function and pregnancy: molecular mechanisms.

Pregnancy and the postpartum period have a profound effect on autoimmune thyroid disease. Graves disease ameliorates during pregnancy, only to relapse postpartum, whereas postpartum thyroiditis is caused by destructive thyroiditis during the first few months after delivery. The immunology of pregnancy underlies these changes: the mother must maintain tolerance of the fetal semi-allograft while not suppressing her own immune system and exposing herself and the fetus to infection. Nonspecific factors, including hormonal changes, trophoblast expression of key immunomodulatory molecules and a switch to a predominantly T-helper-2-type pattern of cytokines, play some part in the maintenance of transient tolerance to paternal antigens in pregnancy; however, the generation of specific regulatory T (T(REG)) cells is key to this maintenance. T(REG) cells preferentially accumulate in the decidua but may also be present in the mother's circulation and are thus capable of regulating coincidental autoimmune responses through the phenomenon of linked suppression. In turn, this suppression may explain why thyroid autoantibody levels decline during pregnancy, which leads to remission of Graves disease. Postpartum exacerbation of autoimmunity may reflect an imbalance in T(REG) cells, which is caused by the rapid fall in the numbers of these cells after delivery.

C4BPB/C4BPA is a new susceptibility locus for venous thrombosis with unknown protein S-independent mechanism: results from genome-wide association and gene expression analyses followed by case-control studies.

Through its binding with protein S (PS), a key element of the coagulation/fibrinolysis cascade, the C4b-binding protein (C4BP) has been hypothesized to be involved in the susceptibility to venous thrombosis (VT). To identify genetic factors that may influence the plasma levels of the 3 C4BP existing isoforms, alpha(7)beta(1), alpha(6)beta(1), and alpha(7)beta(0), we conducted a genome-wide association study by analyzing 283 437 single nucleotide polymorphisms (SNPs) in the Genetic Analysis of Idiopathic Thrombophilia (GAIT) study composed of 352 persons. Three SNPs at the C4BPB/C4BPA locus were found genome-wide significantly associated with alpha(7)beta(0) levels. One of these SNPs was further found to explain approximately 11% of the variability of mRNA C4BPA expression in the Gutenberg Heart Study composed of 1490 persons, with no effect on C4BPB mRNA expression. The allele associated with increased alpha(7)beta(0) plasma levels and increased C4BPA expression was further found associated with increased risk of VT (odds ratio [OR] = 1.24 [1.03-1.53]) in 2 independent case-control studies (MARseille THrombosis Association study [MARTHA] and FActeurs de RIsque et de récidives de la maladie thromboembolique VEineuse [FARIVE]) gathering 1706 cases and 1379 controls. This SNP was not associated with free PS or total PS. In conclusion, we observed strong evidence that the C4BPB/C4BPA locus is a new susceptibility locus for VT through a PS-independent mechanism that remains to be elucidated.

Circulation levels of acute phase proteins in patients with Takayasu arteritis.

OBJECTIVE: Takayasu arteritis (TA) is an immune-mediated disease with an unknown etiology. Assessment of disease activity in patients with TA is challenging owing to the absence of reliable serologic markers. Because circulation levels of acute-phase proteins fluctuate with the severity and extent of the inflammatory reaction, they may be potential biomarkers for the identification of TA activity. To test this hypothesis, certain acute-phase proteins were examined in TA patients and controls. METHODS: The study included 43 prospectively selected TA patients, with 18 in active phase and 25 in inactive phase. The Sharma modified criteria were used for disease diagnosis, and the National Institutes of Health criteria were used for TA activity assessment. Circulation levels of acute-phase proteins, including serum amyloid A (SAA), fibrinogen, complement C4-binding protein (C4BP), C-reactive protein, serum amyloid P, haptoglobin, alpha-acid glycoprotein, transthyretin, alpha1-microglobin, and complement fraction C3c and C4a were investigated by enzyme-linked immunosorbent assay in each participant. RESULTS: Circulating levels of SAA and C4BP were significantly increased in active TA patients compared with inactive TA patients and in controls, with (SAA: 95.9 [interquartile range, 51.9] vs 49.2 [82.0], P = .009; and 23.9 [50.1] mg/L, P = .001, respectively; C4BP: 88.5 [72.6] vs 61.7 [57.7], P = .023; and 32.6 [32.1] mg/L, P < .001, respectively). The levels of both proteins in inactive TA patients were still higher than those in controls (SAA: 49.2 [82.0] vs 23.9 [50.1] mg/L, P = .021; C4BP: 61.7 [57.7] vs 32.6 [32.1] mg/L, P = .025). No difference was found in the levels of the other acute-phase proteins studied. CONCLUSIONS: SAA and C4BP may be useful biomarkers in determining the disease activity of TA. More work should be done to test these results in a large cohort of patients in a longitudinal manner.

A systems biology approach to understanding elevated serum alanine transaminase levels in a clinical trial with ximelagatran.

Ximelagatran was developed for the prevention and treatment of thromboembolic conditions. However, in long-term clinical trials with ximelagatran, the liver injury marker, alanine aminotransferase (ALT) increased in some patients. Analysis of plasma samples from 134 patients was carried out using proteomic and metabolomic platforms, with the aim of finding predictive biomarkers to explain the ALT elevation. Analytes that were changed after ximelagatran treatment included 3-hydroxybutyrate, pyruvic acid, CSF1R, Gc-globulin, L-glutamine, protein S and alanine, etc. Two of these analytes (pyruvic acid and CSF1R) were studied further in human cell cultures in vitro with ximelagatran. A systems biology approach applied in this study proved to be successful in generating new hypotheses for an unknown mechanism of toxicity.

Complement inhibitor C4b-binding protein in primary Sjögren's syndrome and its association with other disease markers.

A subgroup of patients suffering from primary Sjögren's syndrome (pSS) display unexplained low levels of complement components C3 and/or C4 which is associated with increased risk of non-Hodgkin's lymphoma. C4b-binding protein (C4BP) is a major fluid-phase complement inhibitor which can influence C4 and C3 levels. Therefore we analysed C4BP levels in the sera of patients with pSS to better understand the disturbances in complement in pSS. Associations with other disease markers were also investigated to define a possible role of C4BP as marker of high-risk disease course. Plasma levels of C4BP were analysed in pSS patients (n=86) and in controls (n=68) by ELISA. C4BP levels from 49 patients were correlated to disease activity markers and autoantibody profiles. We found that total C4BP plasma levels were significantly higher in pSS patients compared with controls. C4BP levels correlated to the acute phase response, to levels of C4 and C3 as well as to the CD4+/CD8+ T-cell ratio. C4BP levels were inversely related to IgG levels, extent of autoantibody production and global disease activity. C3dg levels, a marker of complement activation, displayed a negative correlation to C4 levels but interestingly not to C4BP levels. In conclusion, C4BP levels are increased in patients suffering from pSS proportional to their acute phase response. However, in the most active cases, with the most widespread autoantibody production, C4BP levels were decreased in parallel with levels of C3 and C4 and CD4+ T cells, suggesting that disturbed complement regulation may contribute to pathogenicity in pSS.

Protein S deposition at placenta: a possible role of protein S other than anticoagulation.

Protein S is an antithrombotic cofactor for protein C that also has multifunctional anti-inflammatory, cellular protective, apoptotic and mitogenic properties. Protein S levels are thought to decrease during pregnancy, but the underlying mechanism remains unknown. We compared protein S concentrations throughout normal pregnancy with those of nonpregnant women and measured plasma C4b-binding protein levels in nonpregnant women and in pregnant women at the 40th gestational week. We also examined protein S and C4b-binding protein in the placenta by immunohistochemical staining at early (20th gestational week) and late (40th gestational week) stages of pregnancy. Plasma protein S activity and free protein S-antigen levels significantly decreased from the 10th gestational week and total protein S antigen decreased from the 20th. C4b-binding protein levels between pregnant and nonpregnant women did not significantly differ. The stainable portion of protein S was located at the fetomaternal interface, particularly at degenerative villi. C4b-binding protein was weakly stained at the same areas as protein S. Neither protein S nor C4b-binding protein were stained at normal villi. These results indicated that protein S can protect or restore damaged villi via a physiological effect in addition to its anticoagulation properties.

Alloreactivity and anti-tumor activity segregate within two distinct subsets of cytokine-induced killer (CIK) cells: implications for their infusion across major HLA barriers.

Donor-derived cytokine-induced killer (CIK) can be infused as adoptive immunotherapy after hematopoietic cell transplant (HCT). Promising results were recently reported in HLA-identical HCT, where mild grafts versus host (GVH) events were observed. To extend this strategy across major HLA barriers (e.g. HLA-haploidentical HCT), further studies on CIK cells' alloreactivity are needed. We hypothesized that alloreactivity and anti-tumor activity of CIK cells segregate within two different cell subsets and could consequently be separated according to CD56 and CD3 expression. We tested CIK cells expanded from seven patients who underwent HCT as treatment of metastatic colorectal cancer. We found that CIK cells maintained their alloreactivity across major HLA barriers when tested as bulk population; after CD56-positive selection, anti-tumor activity was restricted to the CD3+/CD56+ cell fraction and alloreactivity versus HLA-mismatched PBMC was restricted to the CD3+/CD56- cell fraction. Bulk CIK cells from engrafted patients did not exhibit alloreactivity in response to host- or donor-derived PBMC, confirming their low potential for GVH across minor HLA barriers. Moreover, we tested if CIK cells expanded from engrafted patients after HCT were as effective as donor-derived ones and could be considered as an alternative option. The expansion rate and tumor cell killing was comparable to that observed in sibling donors. In conclusion, depletion of CD3+/CD56- cells might reduce the risk of GVH without affecting the tumor-killing capacity and could help extending CIK infusions across major HLA barriers. Engrafted patients after HCT could also be considered as an effective alternative option to donor-derived CIK cells.

Antiphospholipid antibodies and acute-phase response in non-metastatic colorectal cancer patients.

AIM: To investigate the plasma levels and prevalence of the most common antiphospholipid antibodies, as well as their relationships with several plasma markers of inflammation, in order to characterize some aspects of cancer thrombophilia. MATERIALS AND METHODS: Eighty-three cancer patients with non-metastatic colorectal solid tumors and 94 control subjects were tested for the presence of IgG/IgM/IgA anti-cardiolipin and anti-Beta2-glycoprotein I antibodies and of several acute-phase reactants, i.e., fibrinogen, factor VIII:C and C4b-binding protein. RESULTS: In cancer patients the plasma levels of the acute-phase reactants and the IgA/IgG anti-cardiolipin and IgA anti-Beta2- glycoprotein I antibodies were significantly higher; the acute-phase reactants were significantly correlated with anti-cardiolipin antibodies; the prevalence of antiphospholipid antibodies was not significantly higher. CONCLUSIONS: In patients with non-metastatic colorectal cancer the acute-phase response is associated with antiphospholipid generation. This could represent a further pathogenetic mechanism for the short-term post-surgery thrombotic complications of patients with colorectal cancer.

Coagulation factor levels in non-metastatic colorectal cancer patients.

UNLABELLED: There is evidence that high plasma levels of factor (F) VIII, FIX, FXI and fibrinogen are independent risk factors for venous thromboembolism. AIM: To determine the plasma concentrations of several coagulation factors and C4b-binding protein (C4BP) in a group of patients with non-metastatic colorectal cancer in order to investigate some aspects of cancer-acquired thrombophilia. METHODS: Plasma fibrinogen, FII, FV, FVII, FVIII, FIX, FX, FXI and FXII activity levels and C4BP concentrations were determined in 73 patients with non-metastatic colorectal cancer (48 colon and 25 rectum) and in 67 matched control subjects. No one in either group had had previous thrombotic events. RESULTS: Mean plasma concentrations of fibrinogen (functional and antigen), FVIII, FIX, FV and C4BP were significantly higher in colorectal cancer patients than in control subjects, while FVII and FXII levels were significantly decreased. Several correlations were found between the increased coagulation factors and C4BP concentrations, while FVII was highly correlated with FXII. CONCLUSIONS: In colorectal cancer patients high plasma fibrinogen, FVIII and FIX levels might represent further risk factors for venous thrombotic complications in the immediate post-surgery period, while decreased FVII and FXII concentrations may be an index of intravascular coagulation activation, still in a subclinical phase.

Analysis of C4 and the C4 binding protein in the MRL/lpr mouse.

Systemic lupus erythematosus is a complement-mediated autoimmune disease. While genetic deficiencies of classical pathway components lead to an increased risk of developing systemic lupus erythematosus, end organ damage is associated with complement activation and immune complex deposition. The role of classical pathway regulators in systemic lupus erythematosus is unknown. C4 binding protein (C4bp) is a major negative regulator of the classical pathway. In order to study the role of C4bp deficiency in an established murine model of lupus nephritis, mice with a targeted deletion in the gene encoding C4bp were backcrossed into the MRL/lpr genetic background. Compared with control MRL/lpr mice, C4bp knockout MLR/lpr mice had similar mortality and similar degrees of lymphoproliferation. There were no differences in the extent of proteinuria or renal inflammation. Staining for complement proteins and immunoglobulins in the kidneys of diseased mice revealed no significant strain differences. Moreover, there was no difference in autoantibody production or in levels of circulating immune complexes. In comparison with C57BL/6 mice, MRL/lpr mice had depressed C4 levels as early as 3 weeks of age. The absence of C4bp did not impact serum C4 levels or alter classical pathway hemolytic activity. Given that immune complex renal injury in the MRL/lpr mouse is independent of Fc receptors as well as the major negative regulator of the classical pathway, new mechanisms for immune-complex-mediated renal injury need to be considered.

Pregnancy-associated exosomes and their modulation of T cell signaling.

Exosome release by viable cells is a feature of activated cell types, including tumors, fetal cells, and cells of the immune system. Exosomes critically regulate immune activation, by mediating activation-induced cell death. Fetal cells may mimic these events to selectively delete reactive lymphocytes. In this study the presence and composition of placenta-derived exosomes are demonstrated in the maternal circulation along with their consequences on T cell activation markers. For all pregnant patients, exosomes were isolated from sera obtained between 28 and 30 wk gestation. For pregnant women, subsequently delivering at term, circulating levels of placental exosomes were 1.8 times greater than those delivering preterm (p < 0.0001). Exosomes isolated from pregnancies subsequently delivering at term expressed significantly higher levels of biologically active components, including Fas ligand (FasL) and HLA-DR, than those from pregnancies delivering preterm. Standardizing for protein concentrations, exosomes from term-delivering pregnancies exhibited greater suppression of CD3-zeta and JAK3 than those delivering preterm. The suppression of CD3-zeta and JAK3 correlated with exosome expression levels of FasL (r2= 0.92 and r2= 0.938, respectively). Fractionation of exosomes from term-delivering pregnancies by continuously eluting electrophoresis indicated that intact 42 kD FasL and an unidentified 24-kDa protein were associated with CD3-zeta suppression. Our results demonstrated that exosomes from pregnancies ultimately delivering at term are present at significantly greater concentrations than those from pregnancies delivering preterm; however, exosomes from term-delivering pregnancies also exhibit significantly greater suppression of CD3-zeta and JAK3.

Protein S in cancer patients with non-metastatic solid tumours.

AIMS: To study protein S, as an acute phase protein, for its relationships with C4b-BP (C4BP), fibrinogen and Factor VIII:C in a group of patients with solid tumours, without proven metastases. METHODS: Eighty-one consecutive patients with gastrointestinal or pelvic adenocarcinoma (TNM staging: T1-3, N0-2, M0) and 58 healthy subjects were evaluated for plasma free and total protein S antigen, protein S activity, C4BP, fibrinogen and Factor VIII:C. RESULTS: When compared to the control group, the total protein S, the C4BP, the fibrinogen and the Factor VIII:C mean levels were significantly higher in the cancer group, but there was no significant difference for the free and the functional protein S mean concentrations. In both groups the free protein S was correlated with the functional and the total protein S; moreover the latter was significantly correlated with the C4BP, whereas it was significantly correlated with the fibrinogen and the Factor VIII:C only in the cancer group. In addition, a high correlation was found among the C4BP, the fibrinogen and the Factor VIII:C. CONCLUSIONS: Our data show that in these patients there is an acute phase response and suggest that, in the thrombophilic early cancer screening, determination of free protein S is redundant.

Binding of the complement inhibitor C4bp to serogroup B Neisseria meningitidis.

Neisseria meningitidis (meningococcus) is an important cause of meningitis and sepsis. Currently, there is no effective vaccine against serogroup B meningococcal infection. Host defense against neisseriae requires the complement system (C) as indicated by the fact that individuals deficient in properdin or late C components (C6-9) have an increased susceptibility to recurrent neisserial infections. Because the classical pathway (CP) is required to initiate efficient complement activation on neisseriae, meningococci should be able to evade it to cause disease. To test this hypothesis, we studied the interactions of meningococci with the major CP inhibitor C4b-binding protein (C4bp). We tested C4bp binding to wild-type group B meningococcus strain (H44/76) and to 11 isogenic mutants thereof that differed in capsule expression, lipo-oligosaccharide sialylation, and/or expression of either porin (Por) A or PorB3. All strains expressing PorA bound radiolabeled C4bp, whereas the strains lacking PorA bound significantly less C4bp. Increased binding was observed under hypotonic conditions. Deleting PorB3 did not influence C4bp binding, but the presence of polysialic acid capsule reduced C4bp binding by 50%. Bound C4bp remained functionally active in that it promoted the inactivation of C4b by factor I. PorA-expressing strains were also more resistant to C lysis than PorA-negative strains in a serum bactericidal assay. Binding of C4bp thus helps Neisseria meningitidis to escape CP complement activation.

Intralesional immunotherapy of warts with mumps, Candida, and Trichophyton skin test antigens: a single-blinded, randomized, and controlled trial.

BACKGROUND: Warts occur commonly in humans. Destructive modalities are generally the first physician-administered therapy. Other treatment options include immunotherapy. Intralesional immunotherapy using mumps, Candida, or Trichophyton skin test antigens has proved efficacy in the treatment of warts. OBJECTIVES: To determine rates of wart resolution in response to injection of antigen alone, antigen plus interferon alfa-2b, interferon alfa-2b alone, and normal saline; and to compare response according to viral type, major histocompatibility complex antigens, and peripheral blood mononuclear cell proliferation to autologous human papillomavirus antigen before and after injection. DESIGN: Randomized, single-blinded, placebo-controlled, clinical trial. SETTING: Medical school-based dermatology department. PATIENTS: Two hundred thirty-three patients clinically diagnosed as having 1 or more warts. Main Outcome Measure Clinical resolution of warts in response to intralesional immunotherapy. RESULTS: Responders were observed in all treatment arms, but were significantly more likely to have received antigen (P<.001). Resolution of distant untreated warts was observed, and was significantly more likely in subjects receiving antigen (P<.001). Interferon did not significantly enhance the response rate (P = .20) and did not differ from normal saline (P = .65). No viral type or major histocompatibility complex antigen correlated with response or lack of response (P>.99 and P = .86, respectively). A positive peripheral blood mononuclear cell proliferation assay result (2 times pretreatment levels) was significantly more likely among responders (P = .002). While there was no significant difference in response based on sex (P = .56), older subjects (>40 years) were less likely to respond (P = .01). CONCLUSIONS: Intralesional immunotherapy using injection of Candida, mumps, or Trichophyton skin test antigens is an effective treatment for warts, as indicated by significantly higher response rates and distant response rates in subjects receiving antigen. Viral type and major histocompatibility complex antigens did not seem to influence treatment response. Response is accompanied by proliferation of peripheral blood mononuclear cells to human papillomavirus antigens, suggesting that a human papillomavirus-directed cell-mediated immune response plays a role in wart resolution.

Single-step purification of human C4b-binding protein (C4BP) by affinity chromatography on a peptide derived from a streptococcal surface protein.

Many Gram-positive bacteria express surface proteins that bind human plasma proteins. These bacterial proteins, and derivatives of them, are of interest for analysis of bacterial pathogenesis and as immunochemical tools. Well-characterized examples include the IgG-binding reagents staphylococcal protein A and streptococcal protein G, and the recently described streptococcal IgA-binding peptide Sap. Here, we show that a peptide derived from the streptococcal M22 protein can be used for single-step affinity purification of the human complement regulator C4b-binding protein (C4BP). Binding of C4BP was strongly enhanced by dimerization of the peptide via a C-terminal cysteine residue not present in the intact M22 protein. The purified C4BP had the expected binding characteristics, and acted as a cofactor for factor I in the degradation of C4b. Passage of serum through a peptide column under non-saturating conditions resulted in binding of >99.5% of serum C4BP, implying that such a column can be used to deplete serum of C4BP. These data indicate that the C4BP-binding peptide is a versatile tool that can be used for simple and rapid purification of biologically active human C4BP or for removal of C4BP from serum.

Identification and evaluation of major histocompatibility complex antigens in chicken chimeras and their relationship to germline transmission.

Chimeric chickens were evaluated as an intermediate for development of transgenic chickens. The transfer of Barred Plymouth Rock (BR) blastodermal cells into White Leghorn (WL) embryos results in BR-->WL chimeras, and some breeder males generate over 30% germline transmission of the BR genotype to offspring based on a feather-color trait. The objectives of the current study were to 1) identify the MHC (B haplotypes) in resident BR and WL lines, 2) establish that B antigens could be detected and quantified in red blood cells (RBC) of chimeras, 3) establish if there is a correlation in chimeras between percentage of RBC with donor B antigens and percentage germline transmission, and 4) evaluate if the MHC genotype influences chimera development. The RBC agglutination data indicated three B haplotypes were present in each line. The B*2-like, and B*19-like genes were unique to the WL line, and B*13-like and B-15-like genes were unique to the BR line, whereas a B*21-like gene was present in both lines. In adult BR-->WL chimeras, as well as 10- to 14 d-old WL-->WL chimeras, donor-type B antigens were detectable and quantifiable on RBC using flow cytometry. In BR-->WL chimeras, the percentage germline transmission was significantly correlated with the percentage of RBC with donor B antigen, as well as percentage of black feathers in the plumage. In a retrospective study using previously developed BR-->WL chimeras, the level of chimerism and germline transmission was higher in B*21/*21 type recipients, but this was not statistically significant in two prospective studies. It was concluded that MHC antigens on RBC can be used for identifying, quantifying, and selecting chicken chimeras developed by the transfer of blastodermal cells.