Polyclonal activation of immunoglobulin secretion in B lymphocytes induced by staphylococcal peptidoglycan

Staphylococcal peptidoglycan (PG) is a B cell mitogen and immunomodulator in mice. The ability of PG to induce the secretion of polyclonal antibodies in murine lymphocyte cultures was studied using the protein A hemolytic plaque assay. PG was as effective as or more effective than lipopolysaccharide as an inducer of polyclonal antibodies in spleen, lymph node, and bone marrow lymphocytes. The highest numbers of immunoglobulin (Ig) secreting cells were induced in the spleen, and the lowest in the bone marrow cell cultures. All major classes of Ig (IgM, IgG, and IgA) were induced, and the maximal numbers of Ig-secreting cells were detected between days 4 and 5 of culture. The induction of Ig secretion by Pg was T cell, 2-mercaptoethanol, and to a large extent macrophage independent.