Interleukin 2 as an inducer of proliferation in Klebsiella-stimulated human B cells

Klebsiella membranes (KLEBS M), a membrane preparation from Klebsiella pneumoniae, acts as a T-cell independent polyclonal B-cell activator (PBA), stimulating B cells to mature into Ig-secreting cells without prior proliferation. The KLEBS M-activated B cells express Tac antigen. Recombinant interleukin 2, used in costimulation with KLEBS M, induces proliferation and increases the Ig secretion of B cells. On the other hand, KLEBS M-activated B cells do not respond to human BCGF. The lack of proliferation in KLEBS M-stimulated mononuclear cells is shown to be due to the inability of this PBA to induce the production of interleukin 2 in T cells.