Immunohistochemical study on the reactivity of workshop monoclonal antibodies with sheep lymph nodes

Immunohistochemical study of the local immune response in lambs experimentally infected with Dicrocoelium dendriticum (Digenea)

Phenotypic expression of inflammatory cells in liver and hepatic lymph nodes (HLN) has been examined in lambs experimentally infected with Dicrocoelium dendriticum using immunohistochemical techniques. Thirty-two lambs, 12 infected with 1,000 D. dendriticum metacercariae, 12 with 3,000, and 8 controls were used. Half the lambs in each group were slaughtered on days 60 and 180 post-infection (p.i.), respectively. Primary antibodies (Abs) against T cell epitopes (CD3+, CD4+, CD8+ and WC1+ gammadelta), B cell epitopes (CD79alphacy+, CD45R+), immunoglobulin (IgG)-bearing plasma cells, macrophages (CD14+, VPM32+) and major histocompatibility complex (MHC) class IIbeta antigen were used. T lymphocytes (CD3+, CD4+ and CD8+) and B lymphocytes (CD79alphacy+ and CD45R+) with diffuse pattern or forming lymphoid aggregates and follicles surrounded the septal bile ducts (SBD) and inter-lobular bile ducts, whereas the WC1 gammadelta T cells were scattered. Numerous IgG+ plasma cells were observed around SBD. CD14 and VPM32+ macrophages intermingled with lymphocytes were immunostained by the anti-MHC class IIbeta. This Ab also reacted with lymphoid cells. Likewise, increased positive immunostaining for all Abs used was observed in the HLN of infected lambs. There was no qualitative difference regarding the phenotype expression of inflammatory cells between the lambs infected with D. dendriticum. The humoral and cell-mediated local immune responses observed were similar in the two groups of lambs infected with different doses.

A new epitope on sheep CD45R molecule detected by a monoclonal antibody

This paper describes the production and characterization of a monoclonal antibody (mAb), Co-46D5, which recognizes a new epitope on the isoform of the homologous sheep leukocyte common antigen (LCA) or CD45. This nmAb was submitted to the 3rd workshop on ruminant leukocyte antigens and was assigned to a cluster reactive with B- and T-cells subsets. Co-46D recognizes a 220 kDa molecule on peripheral blood mononuclear cells (PBMC) and spleen cells but not on thymocytes. Flow cytometry (FCM) analysis shows that Co-46D5 reacted with 30% of PBMC and 50% of spleen cells and more than 95% of cells freshly isolated from lymphoid follicles of the ileal Peyer's patches (IPP) of young lambs. By immunohistochemistry, the antigen was detected mainly on B-cell areas of lymph nodes and spleen. It was also found on a subpopulation of medullar thymocytes. Based on these results, we assume that Co-46D5 recognizes a new epitope on the largest isoform of the sheep CD45 receptor, probably on the homologous to the human CD45RA isoform.

Flow cytometric analysis of the reactivity of workshop monoclonal antibodies on sheep lymph node cells, after infection with Salmonella abortusovis

Of the 302 monoclonal antibodies included in the Third Workshop on Ruminant Leukocyte Antigens, 167 have been tested for their reactivity on uninfected and Salmonella-infected sheep lymph node leukocytes using FACS analysis. Only 47 of them showed specificities which could be related to those of some control monoclonal antibodies, such as the anti-CD5, anti-Ig light chain and anti-MHC Class II monoclonal antibodies.

Ruminant cluster CD14

Following the analysis of flow cytometry data on ovine and bovine cells and immunoprecipitation, immunohistochemistry and competitive binding studies, a cluster of three monoclonal antibodies (mAbs) (VPM65, VPM66 and VPM67) appeared to be specific for the ruminant CD14 (Gupta, V.K., McConnell, I., Dalziel, R.G. and Hopkins, J., 1996. Identification of the sheep homologue of the monocyte cell surface molecule-CD14. Vet. Immunol. Immunopathol. in press; Hopkins, J. and Gupta, V.K., 1996. Characterization of 3rd Worshop monoclonal antibodies specific for sheep macrophages/monocytes. Vet. Immunol. Immunopathol., 52:329-339). According to flow cytometry results from human CD14-transfected COS-7 cells and from bovine peripheral blood mononuclear cells, another mAb (CC-G33), not submitted to the Workshop, recognised a bovine CD14 epitope which is conserved in the human CD14 (Sopp, P., Kwong, L.S. and Howard, C.J., 1996. Identification of bovine CD14. Vet. Immunol. Immunopathol., 52: 323-328).