Formalin-treated bacteria as selective B cell mitogens in the study of lymphocytes from patients with hypogammaglobulinaemia.

Staphylococcus aureus strain Cowan I, Haemophilus influenzae, and Branhamella catarrhalis that stimulate human B lymphocytes, but not T lymphocytes, were used to study the B lymphocyte function in patients with hypogammaglobulinaemia. Lymphocytes from two patients with no circulating B cells were not stimulated to increased DNA synthesis by these bacterial mitogens. The lymphocytes of six patients with hypogammaglobulinaemia and normal numbers of circulating B cells responded to the bacterial mitogens but in five patients the response was decreased in comparison with healthy controls.