Type of lymphocytes affected by the islet-activating protein (IAP)

Abstract By flow cytometric analysis, we identified the subclass of lymphocytes that proliferates in response to islet-activating protein (IAP), both in vitro (human peripheral blood mononuclear cells, MNC, cultured with IAP) and in vivo (peripheral blood MNC derived from A/J mice treated with IAP). IAP caused a preferential proliferation of CD8 + T cells. These cells expressed the IL-2 receptors on their surface. CD4 + CD8 + T cells could also be detected in these cultures. IAP caused human MNC to produce IL-1 and to induce expression of HLA-DR antigen. These effects may play an important role in the T-cell proliferation induced by IAP, although IAP by itself suppressed the proliferative action of IL-1 in mouse thymocytes. IAP induced proliferation of the purified CD4 + cells but had a smaller effect on the purified CD8 + cells. This suggests that the proliferation of CD8 + cells in IAP-treated MNC depends on the function of other types of cell, e.g. CD4 + cell and macrophage.