Identification of individual goat animals by means of near infrared spectroscopy and chemometrics analysis of commercial meat cuts.

Although the identification of animal species and muscles have been reported previously, no studies have been found on the use of NIR spectroscopy to identify individual animals from the analysis of commercial meat cuts. The aim of this study was to evaluate the use of a portable near infrared (NIR) instrument combined with classical chemometrics methods [principal component analysis (PCA) and partial least squares discriminant analysis PLS-DA)] to identify the origin of individual goat animals using the spectral signature of their commercial cut. Samples were collected from several carcasses (6 commercial cuts x 24 animals) sourced from a commercial abattoir in Queensland (Australia). The NIR spectra of the samples were collected using a portable NIR instrument in the wavelength range between 950 and 1600 nm. Overall, the PLS-DA models correctly classify 82% and 79% of the individual goat samples using either the goat rack or loin cut samples, respectively. The study demonstrated that NIR spectroscopy was able to identify individual goat animals based on the spectra properties of some of the commercial cut samples analysed (e.g. loin and rack). These results showed the potential of this technique to identify individual animals as an alternative to other laboratory methods and techniques commonly used in meat traceability.

The ability of a portable near infrared instrument to evaluate the shelf-life of fresh and thawed goat muscles.

The objective of this study was to evaluate the use of a portable near infrared (NIR) instrument to monitor the shelf-life of four goat muscles [longissimus thoracis et lumborum (LTL), semimembranosus (SM), semitendinosus (ST) and biceps femoris (BF)] stored for up to 8 days (4 °C). The NIR spectra of the muscle samples were collected at day 0, and after 1, 4 and 8 days of storage using a MicroNIR instrument (900-1600 nm). The coefficient of determination in cross-validation (R2) and the standard error in cross validation (SECV) obtained for the prediction of days of storage ranged between 0.76 and 0.86, where the SECV ranged from 0.32 to 0.41. The best statistics in cross-validation were obtained for the prediction of days of storage in the BF samples, followed by the ST and LTL muscles. Differences in the PLS loadings for the cross-validation models were observed due to the interactions between the different muscle samples and days of storage. Overall, these results showed the potential of NIR spectroscopy to identify the time of storage in four different goat muscles. Similar data and techniques could be used to predict the remaining shelf life of meat derived from different species under storage. This information can then be used as a tool to predict and guarantee the safety of meat samples to the consumer along the meat supply and value chains.

Discrimination of lamb (Ovis aries), emu (Dromaius novaehollandiae), camel (Camelus dromedarius) and beef (Bos taurus) binary mixtures using a portable near infrared instrument combined with chemometrics.

Consumers demand safe and nutritious foods at accessible prices; where issues associated with adulteration, fraud, and provenance have become important aspects to be considered by the modern food industry. There are many analytical techniques and methods available to determine food composition and quality, including food security. Among them, vibrational spectroscopy techniques are at the first line of defence (near and mid infrared spectroscopy, and Raman spectroscopy). In this study, a portable near infrared (NIR) instrument was evaluated to identify different levels of adulteration between binary mixtures of exotic and traditional meat species. Fresh meat cuts of lamb (Ovis aries), emu (Dromaius novaehollandiae), camel (Camelus dromedarius) and beef (Bos taurus) sourced from a commercial abattoir were used to make different binary mixtures (95 % %w/w, 90 % %w/w, 50 % %w/w, 10 % %w/w and 5 % %w/w) and analysed using a portable NIR instrument. The NIR spectra of the meat mixtures was analysed using principal component analysis (PCA), and partial least squares discriminant analysis (PLS-DA). Two isosbestic points corresponding to absorbances at 1028 nm and 1224 nm were found to be consistent across all the binary mixtures analysed. The coefficient of determination in cross validation (R2) obtained for the determination of the per cent of species in a binary mixture was above 90 % with a standard error in cross validation (SECV) ranging between 12.6 and 15 %w/w. Overall, the results of this study indicate that NIR spectroscopy can determine the level or ratio of adulteration in the binary mixtures of minced meat.

Response to azacitidine in patients with chronic myelomonocytic leukemia according to overlap myelodysplastic/myeloproliferative neoplasms criteria.

BACKGROUND: Azacitidine (AZA) is approved for the treatment of high-risk chronic myelomonocytic leukemia (CMML) of myelodysplastic (MD) subtype. Data of response rates using the specific response criteria for this disease are scarce. The aim of this study was to evaluate the response to AZA in patients diagnosed with CMML from the Spanish Registry of Myelodysplastic Syndromes (MDS) applying the overlap myelodysplastic/myeloproliferative neoplasms (MDS/MPN) response criteria. METHODS: We retrospectively studied 91 patients with CMML treated with at least one cycle of AZA from the Spanish Registry of MDS. As it was a real-world study, the response rate was evaluated between cycle 4 and 6, applying the MDS/MPN response criteria FINDINGS: The overall response rate at cycle 4-6 was 58%. Almost half of the patients achieved transfusion independence and one quarter showed clinical benefit, regardless of the CMML French-American-British (FAB) and World Health Organization (WHO) subtypes and CMML Specific Prognosis Scoring (CPSS) risk groups. Toxicity was higher in the MD-CMML subtype. INTERPRETATION: In our series, most CMML patients achieved an overall response rate with AZA according to the overlap-MDS/MPN response criteria regardless of the CMML FAB and WHO subtypes and CPSS risk groups. Thus, AZA may also be a treatment option for patients with the myeloproliferative CMML subtype and those with a lower-risk CPSS, but symptomatic.

Inhibition of serotonin receptor type 1 in acute myeloid leukemia impairs leukemia stem cell functionality: a promising novel therapeutic target.

Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous neoplasia with poor outcome, organized as a hierarchy initiated and maintained by a sub-population with differentiation and self-renewal capacities called leukemia stem cells (LSCs). Although currently used chemotherapy is capable of initially reducing the tumor burden producing a complete remission, most patients will ultimately relapse and will succumb to their disease. As such, new therapeutic strategies are needed. AML cells differentially expressed serotonin receptor type 1 (HTR1) compared with healthy blood cells and the most primitive hematopoietic fraction; in fact, HTR1B expression on AML patient samples correlated with clinical outcome. Inhibition of HTR1s activated the apoptosis program, induced differentiation and reduced the clonogenic capacity, while minimal effect was observed on healthy blood cells. In vivo regeneration capacity of primary AML samples was disrupted upon inhibition of HTR1. The self-renewal capacity remaining in AML cells upon in vivo treatment was severely reduced as demonstrated by serial transplantation. Thus, treatment with HTR1 antagonists showed antileukemia effect, especially anti-LSC activity while sparing healthy blood cells. Our results highlight the importance of HTR1 in leukemogenesis and LSC survival and identify this receptor family as a new target for therapy in AML with prognostic value.

The expression level of BAALC-associated microRNA miR-3151 is an independent prognostic factor in younger patients with cytogenetic intermediate-risk acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous disease whose prognosis is mainly related to the biological risk conferred by cytogenetics and molecular profiling. In elderly patients (⩾60 years) with normal karyotype AML miR-3151 have been identified as a prognostic factor. However, miR-3151 prognostic value has not been examined in younger AML patients. In the present work, we have studied miR-3151 alone and in combination with BAALC, its host gene, in a cohort of 181 younger intermediate-risk AML (IR-AML) patients. Patients with higher expression of miR-3151 had shorter overall survival (P=0.0025), shorter leukemia-free survival (P=0.026) and higher cumulative incidence of relapse (P=0.082). Moreover, in the multivariate analysis miR-3151 emerged as independent prognostic marker in both the overall series and within the unfavorable molecular prognostic category. Interestingly, the combined determination of both miR-3151 and BAALC improved this prognostic stratification, with patients with low levels of both parameters showing a better outcome compared with those patients harboring increased levels of one or both markers (P=0.003). In addition, we studied the microRNA expression profile associated with miR-3151 identifying a six-microRNA signature. In conclusion, the analysis of miR-3151 and BAALC expression may well contribute to an improved prognostic stratification of younger patients with IR-AML.

The effect of buffering dairy cow diets with limestone, calcareous marine algae, or sodium bicarbonate on ruminal pH profiles, production responses, and rumen fermentation.

Six ruminally cannulated Holstein cows were used to evaluate the effect of 2 dietary buffers on rumen pH, milk production, milk composition, and rumen fermentation parameters. A high concentrate total mixed ration [35.2% forage dry matter (DM)], formulated to be potentially acidotic, was used to construct 3 dietary treatments in which calcareous marine algae (calcified remains of the seaweed Lithothamnium calcareum) was compared with limestone (control) and sodium bicarbonate plus limestone. One basal diet was formulated and the treatment diets contained either 0.4% of dietary DM as Acid Buf, a calcified marine algae product (AB treatment), or 0.8% of dietary DM as sodium bicarbonate and 0.37% as limestone (BC treatment), or 0.35% of dietary DM as limestone [control (CON) treatment]. Cows were randomly allocated to treatments according to a double 3×3 Latin square design, with 3 treatments and 3 periods. The total experimental period was 66 d during which each cow received each treatment for a period of 15 d before the data collection period of 7 d. Rumen fluid was collected to determine volatile fatty acids, lactic acid, and ammonia concentrations. Rumen pH was monitored every 10min for 2 consecutive days using a portable data logging system fitted with in-dwelling electrodes. Milk samples were analyzed for solid and mineral contents. The effect of treatment on acidity was clearly visible, especially from the period from midday to midnight when rumen pH dropped below 5.5 for a longer period of time (13 h) in the CON treatment than in the BC (8.7 h) and AB (4 h) treatments. Daily milk, 4% fat-corrected milk, and energy-corrected milk yields differed among treatments, with AB being the highest, followed by BC and CON. Both buffers increased milk fat content. Treatment had no effect on milk protein content, but protein yield was increased in the AB treatment. Total rumen volatile fatty acids and acetate concentrations were higher and propionate was lower in the AB treatment than in CON. The molar proportion of acetate was higher in AB than in CON, but that of propionate was lower in both buffer treatments than in CON. The acetate:propionate ratio was increased in the AB and BC treatments compared with CON. Lactic acid concentration was higher in the CON treatment than in the buffer treatments. Treatment had no effect on rumen ammonia concentrations. Results indicated that buffer inclusion in high concentrate diets for lactating dairy cows had a positive effect on milk production and milk composition. Calcareous marine algae, at a level of 90 g/cow per day, had a greater effect on rumen pH, milk production and milk composition, and efficiency of feed conversion into milk than sodium bicarbonate at a level of 180 g/cow per day.

MicroRNA expression at diagnosis adds relevant prognostic information to molecular categorization in patients with intermediate-risk cytogenetic acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous disease, and optimal treatment varies according to cytogenetic risk factors and molecular markers. Several studies have demonstrated the prognostic importance of microRNAs (miRNAs) in AML. Here we report a potential association between miRNA expression and clinical outcome in 238 intermediate-risk cytogenetic AML (IR-AML) patients from 16 institutions in the CETLAM cooperative group. We first profiled 670 miRNAs in a subset of 85 IR-AML patients from a single institution and identified 10 outcome-related miRNAs. We then validated these 10 miRNAs by individual assays in the total cohort and confirmed the prognostic impact of 4 miRNAs. High levels of miR-196b and miR-644 were independently associated with shorter overall survival, and low levels of miR-135a and miR-409-3p with a higher risk of relapse. Interestingly, miR-135a and miR-409-3p maintained their independent prognostic value within the unfavorable molecular subcategory (wild-type NPM1 and CEBPA and/or FLT3-ITD), and miR-644 retained its value within the favorable molecular subcategory. miR-409-3p, miR-135a, miR-196b and mir-644 arose as prognostic markers for IR-AML, both overall and within specific molecular subgroups.

Acute myeloid leukemia with translocation (8;16)(p11;p13) and MYST3-CREBBP rearrangement harbors a distinctive microRNA signature targeting RET proto-oncogene.

Acute myeloid leukemia (AML) with t(8;16)(p11;p13) (t(8;16) AML) has unique clinico-biological characteristics, but its microRNA pattern is unknown. We analyzed 670 microRNAs in seven patients with t(8;16) AML and 113 with other AML subtypes. Hierarchical cluster analysis showed that all t(8;16) AML patients grouped in an independent cluster. Supervised analysis revealed a distinctive signature of 94-microRNAs, most of which were downregulated, including miR-21 and cluster miR-17-92. The mRNA expression analysis of two known transcription factors of these microRNAs (STAT3 and c-Myc, respectively) showed significant downregulation of STAT3 (P=0.04). A bioinformatic analysis showed that 29 of the downregulated microRNAs might be regulated by methylation; we treated a t(8;16) AML sample with 5-aza-2'-deoxycytidine (5-AZA-dC) and trichostatin A and found that 27 microRNAs were re-expressed after treatment. However, there was no difference in methylation status between t(8;16) and other AML subtypes, either overall or in the microRNA promoter. Cross-correlation of mRNA and microRNA expression identified RET as a potential target of several microRNAs. A Renilla-luciferase assay and flow cytometry after transfection with pre-microRNAs confirmed that RET is regulated by miR-218, miR-128, miR-27b, miR-15a and miR-195. In conclusion, t(8;16) AML harbors a specific microRNA signature that is partially epigenetically regulated and targets RET proto-oncogene.

Multicenter evaluation of new double-antigen sandwich enzyme immunoassay for measurement of anti-human immunodeficiency virus type 1 and type 2 antibodies.

A new enzyme immunoassay (EIA), the Cobas Core Anti-HIV-1/HIV-2 EIA DAGS (also referred to as Roche DAGS), for the detection of antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2 was evaluated in four centers. The assay is based on the double-antigen sandwich (DAGS) format, which enables the detection of all classes of antibodies. The antigens consist of recombinant proteins in their native conformation and of synthetic peptides. Of a total of 5,836 negative serum samples, including 95 samples likely to produce false reactivities, 6 were false positive, resulting in a specificity of 99.9%. None of 35 sera that were from noninfected individuals but contained p24-cross-reacting antibodies as revealed by Western blot (immunoblot) analysis were reactive by the Roche DAGS assay. In samples from individuals infected with HIV-1 group M (n = 499) and HIV-2 (n = 200), the sensitivity of the assay was 100%. Although containing antigens with sequences from subtype B only, the assay was also able to correctly identify with high optical density/cutoff ratios samples from subjects infected with HIV-1 subtype O (n = 10). In 17 of 19 seroconversion panels tested, the assay detected the presence of HIV-1 antibodies as early as another sandwich EIA. Eight of these panels were also analyzed by an indirect second-generation assay, which detected antibodies 2 to 10 days later than did the DAGS assay under evaluation. The excellent specificity and sensitivity of the new Cobas Core Anti-HIV-1/HIV-2 EIA DAGS are the result of the DAGS format as well as of the native, naturally folded form of the recombinant protein used as the gag antigen.

Epitopes of the T19 lymphocyte surface antigen are extensively conserved in ruminants.

The reactivity of five monoclonal antibodies (mAbs SBU-T19, 197, IL-A29, CC-15 and CC-39) specific for the T19 molecule on sheep and cattle CD4-CD8- T cells was compared. MAbs SBU-T19 and 197 were shown to recognise separate epitopes on T19. All mAbs reacted with lymphocytes from several different ruminant species and the tissue distribution and frequency of positive cells was similar in each case. None of the mAbs reacted with horse, pig or camel lymphocytes. The extensive conservation of T19 epitopes in ruminants during the mammalian radiation could indicate an important role for this molecule in the ruminant immune system.

T cell receptor gene expression in sheep: differential usage of TcR1 in the periphery and thymus.

We have isolated cDNA clones for each chain of the sheep T cell receptor (TcR) and used these to analyze TcR gene expression in thymocyte and peripheral T cell subsets. Outer cortical thymocytes expressed a low level of mature message for all TcR chains suggesting that intrathymic precursors for the alpha/beta and gamma/delta lineages occur in this population. Inner cortical and medullary thymocytes expressed high levels of mature alpha/beta transcripts, low levels of mature delta transcripts but no detectable gamma message. Mature alpha/beta transcripts were detected in peripheral CD4+ lymphocytes and these as well as CD8+ cells expressed a surface heterodimer of 85 kDa which resolved into 40- and 50-kDa subunits after reduction. Peripheral CD4-CD8-lymphocytes, which in sheep are marked by the T19 antigen and may account for up to 60% of T cells in blood, expressed a surface heterodimer of 75 kDa. The T19+ cells had high levels of mature delta and truncated beta transcripts in their cytoplasm but did not express the C gamma gene detected in DN thymocytes, although they seem to share V gamma and/or J gamma elements. Both forms of the sheep TcR are associated with CD3 molecules on the cell surface. These results show that (a) in contrast to the situation in rodents and humans, a large proportion of peripheral sheep lymphocytes use TcR gamma/delta; (b) the proportion of T cells in the periphery which use TcR gamma/delta is greater than in thymus; and (c) CD4-CD8- cells in thymus and periphery (T19+) use the same C delta gene but appear to use different C gamma genes, suggesting that in sheep there may be more than one lineage of lymphocytes expressing TcR gamma/delta.

Evidence that the B5 molecule on sheep lymphocytes is a homologue of mouse Ly 6 and human CD59.

When analysed by SDS-PAGE, the B5 molecule immunoprecipitated from sheep thymocytes, T cells and B cells migrated as multiple bands within a size range of 11,000-17,000 MW. After digestion with endoglycosidase-F, the precipitate from all cell types yielded a 6000 MW band. T-cell lysates gave an additional band at 6300 MW. All forms of the B5 molecule were anchored to the cell membrane via phosphatidylinositol. These results strengthen earlier evidence that the B5 molecule is a sheep homologue of the mouse Ly 6 antigen. The additional protein unit found on T cells may be of functional importance since the B5 molecule is known to be involved in an activation pathway of T cells but not of thymocytes or B cells.

Gamma/delta T cells express a unique surface molecule appearing late during thymic development.

The vast majority of T cells in man and mouse use the alpha/beta form of T cell receptor (TcR), and express either CD4 or CD8, whereas the small subset of gamma/delta T cells are usually CD4-CD8-. In contrast to man and mouse, the gamma/delta subset in sheep, defined here using an anti-gamma/delta monoclonal antibody (mAb), comprises 30%-60% of T cells. We show that gamma/delta T cells in sheep express a unique surface molecule termed T19 which is 215 kDa in size and unrelated to either CD45 or the TcR. The T19 molecule was expressed at a distinct stage during gamma/delta T cell ontogeny within the thymus, since gamma/delta thymocytes which appeared early in fetal ontogeny were T19- and also major histocompatibility complex (MHC) class I- and localized almost exclusively to the outer cortex and cortex of the thymus. "Mature-type" gamma/delta thymocytes which emerged late in thymic development were T19+ and MHC class I+ and localized predominantly to the thymic medulla. The sequence of events indicated that these cells were most likely derived from the early gamma/delta thymocytes. These medullary gamma/delta thymocytes showed a very distinctive association with Hassall's corpuscles, suggesting a role for these structures in gamma/delta thymocyte maturation. In the periphery, T19 was expressed exclusively within the gamma/delta T cell subset, however some gamma/delta T cells were T19-. In particular, a large proportion of gamma/delta T cells within intestinal epithelium lacked T19, indicating a correlation between T19 expression and either function or homing patterns of gamma/delta T cells. Both T19+ and T19- gamma/delta T cells were CD2-, and expressed low levels of LFA-1 and CD5. In addition, gamma/delta T cells recirculated differently from other T cells, and appeared not to enter mesenteric lymph nodes at all from the blood. We propose that T19 is a maturation marker for gamma/delta T cells. In addition, the exclusive expression of T19 by gamma/delta T cells indicates that this molecule most likely serves a fundamental role in the interactions and function of gamma/delta T cells.

Ontogeny, morphology and tissue distribution of a unique subset of CD4-CD8- sheep T lymphocytes.

The morphology, distribution and ontogeny of the 197+ T lymphocyte subpopulation is described. Cells were identified by immunofluorescent and immunoenzymic staining of cell suspensions and tissue sections. In the circulation, 197+ cells are small and regular, indistinguishable in size from peripheral CD4+ and CD8+ cells, with little cytoplasm and a large amount of condensed chromatin. In the post-natal animal they are unevenly distributed, being most common in the circulatory pathways, particularly in the blood. In the thymus they chiefly localize in the regions around Hassal's corpuscles and medullary blood vessels. They are totally absent from B cell areas in all tissues. They are the last of the T cells to appear in ontogeny, and are first detected in the thymus. Their frequency in blood is age-dependent with peak levels occurring perinatally. There is a post-natal decline in the frequency of 197+ cells in ileocaecal but not in prescapular lymph nodes. We conclude that these T cells differ from the more commonly described T cells, not only in their surface expression of the CD4, CD8 and T19 antigens, but also in the time of their first appearance, their age-related prevalence and their distribution between and within tissues.

A novel glycoprotein expressed on sheep T and B lymphocytes is involved in a T cell activation pathway.

We have produced a new mouse mAb that identifies a sheep T cell activation Ag. The mAb B5-5 is specific for low m.w. components on nearly all sheep thymocytes and peripheral T and B lymphocytes but does not label immature B cells in Peyer's patches or germinal centers. After cross-linking of target structures either directly by plastic-bound mAb or indirectly using anti-Ig reagents, peripheral T cells, but not thymocytes or peripheral B cells, were activated. IL-2 was secreted by T cells after cross-linking and activation was strongly augmented in the presence of PMA. The addition of soluble B5-5 mAb to mitogen-stimulated cultures of sheep lymphocytes resulted in a suppression of PHA responses and augmentation of PWM responses and had a variable effect on Con A responses but had no effect on LPS- or protein A-induced proliferation. When added to alloantigen-stimulated cultures, B5-5 augmented the proliferative response. The B5-5 membrane component consists of 14- to 19-kDa glycoproteins but the banding patterns obtained during SDS-PAGE analysis of 125I-labeled Ag differed between thymocytes, peripheral T cells, and peripheral B cells. On the basis of its range of expression on lymphoid cells and known biochemical and functional properties, we conclude that the B5-5 component on sheep lymphocytes is different from T cell activation Ag in other species.

A murine anti-sheep T8 monoclonal antibody, ST-8, that defines the cytotoxic T lymphocyte population.

A mouse monoclonal antibody (mAb), ST-8, reactive with a subpopulation of sheep T lymphocytes was investigated by tissue distribution analysis and functional studies of the antigen-bearing (ST-8+) cells. Two other mouse mAb, ST-1 and T-80 that recognize all sheep T cells and a T-cell subset, respectively, were also examined for comparison. The ST-8+ cells represented 61-69% of thymocytes and about 10-30% of peripheral T lymphocytes. Histologically, ST-8+ cells were found mainly in the thymic cortex, T-dependent areas of the peripheral lymphoid tissues and the splenic red pulp and marginal zone, but not in B-dependent areas such as germinal centers of lymph follicles of the Peyer's patches. ST-8 mAb plus complement treatment completely abolished both the induction phase and the effector phase of alloreactive cytotoxic T lymphocytes but did not affect proliferative responses to T-dependent mitogens and allogeneic antigens. ST-8 mAb also blocked the cytotoxic T lymphocyte function of lysing specific targets in the absence of complement. ST-8 mAb immunoprecipitated an antigen from the surface of sheep T lymphocytes under reducing conditions with an apparent molecular weight of 33-35 kilodaltons. Therefore the antigen recognized by the ST-8 mAb showed striking similarities to human T8/Leu-2a and mouse Lyt-2 antigens not only in the tissue distribution and function of antigen-bearing cells but also the molecular weight. We conclude that the ST-8 antigen is the ovine homologue of the human T8 and mouse Lyt-2 antigens.

Studies on the differentiation of T lymphocytes in sheep. III. Preliminary characterization of an antigen recognized by two anti-pan T-cell monoclonal antibodies.

ST-1a and ST-1b are monoclonal antibodies that selectively react with cells in the T-cell lineage of the sheep. Preliminary structural studies using radioimmunoprecipitation and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) indicated that both ST-1a and ST-1b recognize an antigen of apparent molecular weight 67,000 and 60,000-65,000, under either reducing or nonreducing conditions. Differential expression of these 67,000 and 60,000-65,000 MW proteins was observed in T cells obtained from various anatomical compartments. Cortical thymocytes and efferent lymph lymphocytes expressed predominantly the 67,000 molecule, whereas a thymus cell fraction enriched for medullary thymocytes expressed mainly the 60,000-65,000 MW molecule. Both proteins were found in equivalent amounts in immunoprecipitates obtained from peripheral blood lymphocytes and lymph node lymphocytes. Peptide mapping studies indicated that 67,000 proteins of both ST-1a and ST-1b immunoprecipitates have significant homology in peptide composition. Sequential immunoprecipitation experiments clearly demonstrated that the antigens recognized by ST-1a and ST-1b antibodies are the same. On the basis of the size, tissue distribution and trypsin sensitivity of the antigen, together with cytofluorometry data, we suggest that the target antigen of ST-1a and ST-1b monoclonal antibodies is the ovine homologue of mouse Lyt-1 and human Leu-1.

Studies on the differentiation of T lymphocytes in sheep. II. Two monoclonal antibodies that recognize all ovine T lymphocytes.

Two mouse monoclonal cytotoxic antibodies (ST-1a and ST-1b) recognize an antigen present on the large majority of thymocytes and all T cells in the periphery, but not B cells or other haemopoietic cells in sheep. Examination of frozen sections of various fetal tissues revealed that the cells expressing this antigen first appeared in the thymus, and these cells markedly increase in numbers in the peripheral lymphoid tissues after mid-gestation. Large accumulations of positive cells were located in the paracortex of lymph nodes, the periarteriolar lymphoid sheath of the spleen, and interfollicular areas of jejunal Peyer's patches, all of which are known to be T-dependent areas. Treatment of lymphocytes with ST-1a and complement resulted in the abrogation of T-proliferative responses, but the response to a B-cell mitogen, lipopolysaccharide, was not reduced. Neither ST-1a nor ST-1b cross-reacted to lymphocytes obtained from other species of animals (man, monkey, mouse, rat, guinea-pig, chicken, frog, pig, horse, goat and cattle). Based on these findings, it was concluded that the expression of the antigen recognized by ST-1a and ST-1b is restricted to the T-cell lineage of sheep, and that all ovine T cells express this antigen. Furthermore, ST-1a and ST-1b were determined to recognize the same antigen by reciprocal blocking experiments.