Bacillus subtilis selectively stimulates the synthesis of membrane bound and secreted IgA.

Peripheral blood lymphocyte subpopulations and IgA production in vitro have been studied in 30 elderly subjects. Fifteen patients were treated with Bacillus subtilis (Enterogermina, Midy) and 15 with a placebo preparation. At the end of the treatment, a significant increase was noticed in lymphocytes bearing membrane IgA and Ia+ cells in the group treated with Bacillus subtilis, but not in the controls. Similarly, a significantly enhanced spontaneous production of IgA in vitro was seen in the treated subjects. The relevance of these findings to the understanding of the mode of action of Bacillus subtilis and its usefulness in different immunodeficiency states is discussed.