Reactivity of the CD11/CD18 workshop monoclonal antibodies in the sheep.

The anti-CD11/CD18 monoclonal antibodies (mAbs) submitted in the Second International Workshop on Ruminant Leukocyte Differentiation Antigens, were analysed for their reactivity with the ovine homologue of CD11/CD18. Their reactivity was tested on healthy sheep tissues, and alveolar macrophages, afferent dendritic cells, peripheral blood granulocytes and monocytes. The CD11a/CD18 mAbs found positive in the sheep were reactive with all the cell populations tested. The CD11b mAbs reacted with all the cells except afferent dendritic cells, whereas CD11c were non-reactive to blood granulocytes. This is in contrast to humans and cattle where blood granulocytes express CD11c. The mAbs 72-87, F10-150, MD2B7 and MUC76A were found to be homologous to CD11a whereas BAQ30A seemed to be homologous to CD18, instead of proposed initial specificity to CD11a. CC125 and IL-A15 mAbs were found to be homologous to CD11b. OM1, which clustered with a recognized CD1 mAb in the first cluster analysis, precipitated a heterodimer of molecular weight 95,000/150,000. We propose that OM1 reacts with sheep CD11c. The mAb MF14B4 was found to react with sheep CD18.