LAUSR

&NA; Although buffaloes (Bubalus bubalis) are a major component of the livestock industry worldwide, limited progress has been made in the study of the mechanisms regulating the immune response to pathogens and parasites affecting their health and productivity. This has been, in part, attributable to the limited availability of reagents to study immune responses in buffalo. As reported here, a set of cross‐reactive monoclonal antibodies (mAbs), developed against bovine, ovine and caprine leukocyte differentiation molecules (LDM) and major histocompatibility complex (MHC) molecules, were identified and used to compare expression of LDM in Italian and Egyptian buffalo. The results show most of the epitopes identified with the mAbs are conserved on LDM and MHC I and II molecules in both lineages of buffalo. Comparison of the composition of lymphocyte subsets between buffalo and cattle revealed they are similar except for expression of CD2 and CD8 on workshop cluster one (WC1) positive &ggr;&dgr; T cells. In cattle, CD8 is expressed on a subset of CD2+/WC1‐ &ggr;&dgr; T cells that are present in low frequency in blood of young and old animals, whereas, CD8‐/CD2‐/WC1+ &ggr;&dgr; T cells are present in high frequency in young animals, decreasing with age. In the buffalo, CD2 is expressed on a subset of WC1+ &ggr;&dgr; T cells and CD8 is expressed on all WC1+ &ggr;&dgr; T cells. The availability of this extensive set of mAbs provides opportunities to study the immunopathogenesis of pathogens and parasites affecting the health of buffalo. HighlightsMonoclonal antibodies were identified that recognize orthologues of LDMs and MHC I and II molecules in buffalo (Bubalus bubalis).Phenotypic analysis of buffalo lymphocyte subsets showed that all WC1+ &ggr;&dgr; T cells express CD8 with a small subset co‐expressing CD2.The extensive set of cross reactive mAbs will allow for comparison of the similarities and differences in the immune response to pathogens affecting the health of both cattle and buffalo.