Effects of interleukin 4 on neonatal B lymphocyte tolerance

Perturbation of antigen receptors on mouse neonatal B cells by rabbit antimouse IgM antibody was shown to inhibit cell proliferation in response to the B cell mitogen lipopolysaccharide. When these antibody-inactivated cells were challenged with lipopolysaccharide in the presence of the helper T cell product interleukin 4, a strong proliferative response was observed. Interleukin 4 alone did not cause proliferation of the antibody-treated B cells. Pretreatment with interleukin 4 did not prevent neonatal B cell inactivation by the antibody. Our results show that neonatal B cells inactivated directly through their antigen receptors can be reactivated by the combined signals of interleukin 4 and lipopolysaccharide.