Thymus dependence of the IgA response to sheep erythrocytes.

The thumus dependence of the IgA response to sheep red blooc cells (SRBC) was studied by means of cell transfer experiments in mice. Only low numbers of IgM-, IgG- and IgA-plaque-forming cells (PFC) were observed in those recipients which received only spleen cells from adult thymectomized, irradiated and bone marrow-reconstituted mice (B cells). High numbers of IgM-, IgG- and IgA-PFC were observed when B cells and educated T cells were transferred to the recipients. Evidence is provided that B cells committed to IgA synthesis require the same degree of interaction with T cells as B cells committed to IgM synthesis, but a lower degree of interaction with T cells than B cells committed to IgG synthesis.