Lymphocyte surface membrane immunoglobulin in myeloma. III. IgA plasmacytomas induce large numbers of circulating, adult-thymectomy-sensitive, θ ⁺, Lyt-1 ^-2 ⁺ lymphocytes with IgA-Fc receptors

In the present studies we demonstrate that the IgA-FcR ⁺lymphocytes in mice with IgA myeloma re Lyt-1 ^-2 ⁺, short-lived, post-thymic T cells. These features have previously been described in some immunoregulatory T cell populations. We recently demonstrated that the Tα cells found in mice with IgA-secreting myeloma are directly induced by the IgA myeloma protein. Furthermore, large numbers of Tα cells are induced in otherwise normal mice whose serum level of IgA has been experimentally elevated, and Tα cells can be induced by IgA in vitro. Collectively, these studies have identified a potential homeostatic circuit for IgA-producing B cells in which the IgA product of the B cell elicits IgA-specific immunoregulatory T cells.