Formalin-treated bacteria as selective B cell mitogens: results in primary and acquired immunodeficiencies.

The mitogenic activity of the formalin-treated bacterial strains Branhamella catarrhalis, Haemophilus influenzae and the Cowan I strain of Staphylococcus aureus was assessed in peripheral blood lymphocytes (PBL) from patients with primary immunodeficiencies, acute lymphocytic leukaemia (ALL), chronic lymphocytic leukemia (CLL) and in umbilical cord blood lymphocytes. The bacteria selectively stimulated B cells, as demonstrated by the finding of a normal de novo DNA synthesis in children with a T cell defect and of an absent response in X-linked agammaglobulinaemia and severe combined immunodeficiency. A decreased mitogenic activity was exerted on PBL from four out of seven adults with common variable hypogammaglobulinemia (CVH). In B-CLL the mitogenic activity was normal while in T-ALL it was decreased. Umbilical cord blood lymphocytes responded better than PBL from adults. The selective stimulative ability of the bacteria for B lymphocytes is expressed when PBL are cultured together with the formalin-treated bacteria for 48 to 72 hr.