REPORT ON THE ANALYSES OF MAB REACTIVE WITH PORCINE CD8 FOR THE 2ND INTERNATIONAL SWINE CD WORKSHOP

Based on an analysis of their reactivity with porcine peripheral blood lymphocytes (PBL), only three of the 57 mAbs assigned to the T cell/a ctivation marker group were grouped into cluster T9 along with the two wCD8 workshop standard mAbs 76-2-11 (CD8a) and 11/295/33 (CD8b). Thei r placement was verified through the use of two-color cytofluorometry which established that all three mAbs (STH101, #090; UCP1H12-2, #139; and PG164A, #051) bind exclusively to CD8(+) cells. Moreover, like the CD8 standard mAbs, these three mAbs reacted with two proteins with a MW of 33 and 35 kDa from lymphocyte lysates and were, thus, given the wCD8 designation. Because the mAb STH101 inhibited the binding of mAb 76-2-11 but not of 11/295/33, it was given the wCD8a designation. The reactivity of the other two new mAbs in the T9 cluster with the variou s subsets of CD8(+) lymphocytes were distinct from that of the other m embers in this cluster including the standards. Although the character istic porcine CD8 staining pattern consisting of CD8(low) and CD8(high ) cells was obtained with the mAb UCP1H12-2: a hider gap between the f luorescence intensity of the CD8(low) and CD8(high) lymphocytes was ob served. In contrast, the mAb PG164A, not only exclusively reacted with CD4(-)/CD8(high) lymphocytes, but it also failed to recognize CD4/CD8 double positive lymphocytes. It was concluded that this mAb is specif ic for a previously unrecognized CD8 epitope, and was, thus, given the wCD8c designation. A very similar reactivity pattern to that of PG164 A was observed for two other mAbs (STH106, #094; and SwNL554.1, #009). Although these two mAbs were not originally positioned in the T cell subgroup because of their reactivity and their ability to inhibit the binding of PC164A, they were given the wCD8c designation. Overall, fiv e new wCD8 mAbs were identified. Although the molecular basis for the differences in PBL recognition by these mAbs is not yet understood, th ey will be important in defining the role of CD8(+) lymphocyte subsets in health and disease. (C) 1998 Elsevier Science B.V.