RAT PERITONEAL MAST-CELLS PRESENT ANTIGEN TO A PPD-SPECIFIC T-CELL LINE

Rat peritoneal mast cells were examined to determine whether mast cell s can stimulate T cell proliferation through antigen presentation. Mas t cells were obtained by peritoneal lavage and purified to 98% using d ensity gradient centrifugation. Purified peritoneal mast cells express ed MHC class II molecules as determined by flow cytometry using monocl onal antibody OX6 specific for common determinants of rat class II. Th e intensity of class II expression by mast cells was not significantly increased upon incubation with recombinant rat IFN-gamma. Peritoneal mast cells also were found to express the accessory molecules ICAM-1(C D54) and LFA-1 beta (CD18) but not LFA-1 alpha (CD11a). In the presenc e of antigen, purified mast cells stimulated proliferation of an autol ogous CD4(+), PPD-specific T cell line. This stimulation was blocked b y OX6 antibody, confirming that the proliferation was class II depende nt. T cell proliferation was similarly induced by purified mast cell p opulations that were completely monocyte and macrophage depleted. Thes e results demonstrate that mast cells, through their expression of MHC class II and accessory molecules,are capable of antigen presentation. (C) 1994 Academic Press, Inc.