ANTIGEN-SPECIFIC PROLIFERATIVE RESPONSE OF PERITONEAL-EXUDATE LYMPHOCYTES PRIMED WITH ANTIGEN AND BACTERIAL LIPOPOLYSACCHARIDE - THE ROLES OF IA(-2() ACCESSORY CELLS AND IL)

In vitro antigen-specific proliferation was investigated in a lymphocy te population that had been taken from the peritoneal exudate cells (P EC) of C3H/HeN mice (Ia(k)) primed in vivo with both bacterial lipopol ysaccharide (LPS) and horse red blood cells (HRBC) and had been purifi ed by passage through a nylon fiber column (Nfc). The proliferative re sponse of the Nfc-passed lymphocytes primed with HRBC and LPS [T(HRBC + LPS) cells] depended on the dose of antigen in the cultures, and the response was higher than that of cells prepared from mice primed with HRBC alone [T(HRBC) cells]. No response was seen in the cells prepare d from the LPS-primed mice [T(LPS) cells] or normal mice [T(N) cells]. The response of the T(HRBC) cells was abolished by previous treatment of the cells with anti-Ia(k) antibody and complement (C), whereas the response of the T(HRBCS + LPS) cells was retained after the same trea tment, indicating that the Ia(-)T(HRBC + LPS) cells can proliferate in response to antigen in spite of Ia(+) accessory cell-depletion. Super natants from the cultures of Ia- T(HRBC + LPS) cells in the presence o f HRBC showed abundant IL-2 activity, while those of Ia(-)T(HRBC) cell s did not. The IL-2 should be produced by the L3T4 cell population in T(HRBC + LPS) cells in response to antigen, since the previous treatme nt of the cells with anti-L3T4 antibody and C abrogated the production . On the other hand, the Ia(-)T(HRBC+LPS) cells as well as the Ia(-)T( LPS) cells could respond to IL-2 dose-dependently when recombinant IL- 2 was added into the cultures, but the response of Ia(-)T(HRBC) cells to IL-2 was very weak. The cell population responding to IL-2 in the T (HRBC + LPS) cells as well as T(LPS) cells must be AsGM1-positive or n atural killer (NK) cells, since previous treatment of the cells with a nti-AsGM1 antibody and C abrogates the response. Together these result s suggest that L3T4 lymphocytes capable of producing IL-2 in response to HRBC antigen without Ia(+) accessory cells are generated in the PEC of the mice after priming with LPS and antigen together, and the IL-2 produced by the L3T4 lymphocytes induces the proliferation of the LPS -primed AsGM1+ cells.