Molecular and functional characterization of porcine LFA-1 using monoclonal antibodies to CD11a and CD18

We describe in this report the production and characterization of monoclona l antibodies (mAb) to the swine homologues of CD11a and CD18 antigens, and their use for phenotypic and functional analysis of porcine leukocytes. Mon oclonal antibodies BL1H8 and BL2F1 precipitated two bands of approximately 170 and 95 kDa, whereas mAb BA3H2 brought down three bands of 170, 155 and 95 kDa, from alveolar macrophage lysates. Clearance of macrophage lysates w ith mAbs BL1H8 and BL2F1 resulted in complete removal of the 170-kDa band. The cell distribution of the molecules recognized by these mAbs was similar to that of human LFA-1. It was found on all leukocytes, although its expre ssion varied among the different leukocyte subpopulations, with monocytes, granulocytes and a subset of CD8(+) cells expressing the highest levels. Cr oss-blocking studies showed that these antibodies recognize different epito pes on porcine LFA-1. Both anti-LFA-1 mAbs strongly inhibited the mitogenic response of PBMC to ConA, whereas the anti-CD18 mAb had no effect. These a nti-LFA-1 mAbs also inhibited the mixed lymphocyte reaction (MLR) and the N K cell-mediated lysis of K-562 cells.