title: Activation of human B and T lymphocytes by protein A of Staphylococcus aureus.
abstract: Protein A from Staphylococcus aureus, in soluble form or coupled to Sepharose beads, acts as a polyclonal B cell activator (PBA) for human lymphocytes in blood and spleen. PBA activity was demonstrated in spleen cells by the ability of protein A to induce the formation of intracellular immunoglobulin synthesis and to activate polyclonal antibody secretion demonstrated against fluorescein isothiocyanate-coupled sheep erythrocytes in a modified hemolysis in gel assay. More plaqueforming cells (PFC) were seen in unseparated cells than in purified B cells. In blood lymphocytes, only few PFC were activated by soluble protein A. Protein A increased DNA synthesis in blood and spleen cells. At a concentration of 100 microgram/ml the peak response was on day 4 or 5, but at 1 microgram/ml the peak response occurred later. On day 4 of culture, high mitogenic activity was seen in unseparated lymphocytes or mixtures of separated B and T cells, whereas in enriched B and T cell suspensions activity was low. On day 7, however, DNA synthesis in both the enriched B and T cells was higher than in mixtures of B and T cells. Protein A stimulated DNA synthesis in thymus cells with a peak response on day 6. It is concluded that protein A alone or as an IgG complex can activate both B and T cells, though the mechanism of activation is not known and may be different for B and T cells.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D006801:Humans; D037102:Lectins / Q000494:pharmacology; D008213:Lymphocyte Activation; D012685:Sepharose; D012995:Solubility; D013154:Spleen / Q000276:immunology; D013205:Staphylococcal Protein A / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
chemical_list: D037102:Lectins; D013205:Staphylococcal Protein A; D012685:Sepharose