calcimycin and Plasmacytoma

Previously we examined the ability of the host's immune responses to regulate Ig production in an IgE-secreting murine plasma cell tumor (B53). In the present study we have examined the reverse phenomenon, in that we have investigated the effects of this and other plasma cell tumors on the immune responses of their hosts. We found that splenocytes from plasma cell tumor-bearing mice demonstrate decreased proliferation in response to polyclonal stimulation by either Con A or a combination of PMA and calcium ionophore (A23187). Fractionation of the splenocytes demonstrated that this reduction in proliferation was confined to CD4+ T cells and that the proliferation of CD8+ T cells was unaffected. In order to determine whether the down-modulatory effects of the tumor were confined to a particular CD4+ helper T cell subset, we examined the production of cytokines representing the Th1 subset (IL-2 and IFN-gamma) and the Th2 subset (IL-4 and IL-10) from stimulated splenocytes and from stimulated enriched splenic T cells. We found that both stimulated splenocytes and T cells from plasma cell tumor-bearing mice produced lower levels of the Th1 cytokines IL-2 and IFN-gamma compared with normal cultures, demonstrating that Th1-like responses are inhibited in the hosts of these tumors. However, no alterations in the production of the Th2 cytokines IL-4 and IL-10 were observed in these stimulated splenocyte or T cell cultures from the tumor-bearing mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Calcimycin; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Concanavalin A; Cytokines; Female; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Plasmacytoma; Spleen; Tetradecanoylphorbol Acetate; Th1 Cells; Tumor Cells, Cultured