Bacillus firmus (a Gram-positive nonpathogenic and harmless bacterium), was shown to be a strong polyclonal activator of mouse B lymphocytes as estimated by ELISA testing of Ig concentrations in culture supernatants after incubation of BALB/c mouse splenocytes with inactivated bacillus. Synthesis of all main Ig classes and all IgG subclasses was stimulated in vitro, the considerable effect on IgA formation being the most interesting feature. B cell stimulation was T cell dependent, as was demonstrated by the effect of B. firmus on all Ig isotypes and by comparison of lymphocyte response of nu/nu mice and heterozygous nu/+ mice. The effect of B. firmus on splenocyte proliferation was stimulatory or suppressive depending on the dose of the bacterium. Increased synthesis of IFN-gamma and IL-10 (detected by ELISA in splenocyte culture supernatants) showed probable stimulation of Th1 and Th2 subpopulations. Considering the stimulatory effect on IgA formation and macrophage stimulation, B. firmus seems to be a prospective mucosal adjuvant and/or probiotic.

• MeSH
• Lymphocyte Activation * drug effects   MeSH
• B-Lymphocytes drug effects   immunology   MeSH
• Bacillus chemistry   immunology   MeSH
• Enzyme-Linked Immunosorbent Assay MeSH
• Immunoglobulin G biosynthesis   drug effects   MeSH
• Cells, Cultured MeSH
• Mice, Inbred BALB C MeSH
• Mice MeSH
• Antibodies, Bacterial biosynthesis   MeSH
• T-Lymphocytes immunology   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Immunoglobulin G MeSH
• Antibodies, Bacterial MeSH

Bacillus firmus strongly stimulates Ig synthesis in the cultures of human peripheral blood mononuclear leukocytes. As apparent from the character of Ig formation and blastic transformation, the stimulation has features of a polyclonal activation of B lymphocytes without substantial participation of T lymphocytes. B firmus is a strong B cell polyclonal activator even for human cord blood lymphocytes. The most striking feature is the strong stimulation of IgA synthesis in both adult and cord blood lymphocytes. Several crude fractions were isolated from B. firmus. None of them exhibited any remarkable enhancement of activity but the cytoplasmic fraction P-40 was clearly more potent than the intact bacilli. On the other hand, cell wall peptidoglycan, a well known polyclonal activator of B cells, had a much lower activity than whole bacteria. The effect of B. firmus on the stimulation of Ig formation is thus relatively complex; it is not caused mainly by peptidoglycan but rather by some cytoplasmic constituents of the bacterium.

• MeSH
• Lymphocyte Activation * MeSH
• B-Lymphocytes immunology   MeSH
• Bacillus immunology   MeSH
• Adult MeSH
• Fetal Blood cytology   immunology   MeSH
• Humans MeSH
• Peptidoglycan pharmacology   MeSH
• Antibodies, Bacterial biosynthesis   MeSH
• Aging immunology   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Peptidoglycan MeSH
• Antibodies, Bacterial MeSH

B. firmus activates human peripheral blood lymphocytes in vitro. Bacteria inactivated by heat or by formaldehyde were about equally effective, stimulating the blastic transformation of lymphocytes at doses of 10-200 mg/L and Ig formation in the culture at 10-500 mg/L. The action of formaldehyde treated B. firmus was compared with that of analogously inactivated B. subtilis, B. polymyxa, B. coagulans, B. megaterium, B. pumilus, B. cereus and B. lentus at a concentration of 100 mg/L. All these bacilli mildly stimulated blastic transformation and most of them substantially stimulated Ig formation, but B. firmus was the most efficient in stimulating the formation of Ig of all classes, in particular IgM and IgA. Its effect on Ig formation was comparable with that of PWM and was unusually high as compared with that of other bacteria. B. firmus is apparently a strong polyclonal activator of B lymphocytes. Its cells or their components could be potentially used for modulating immune reactions.

• MeSH
• Lymphocyte Activation * drug effects   MeSH
• Bacillus drug effects   physiology   MeSH
• Formaldehyde pharmacology   MeSH
• Immunoglobulin Isotypes biosynthesis   MeSH
• Humans MeSH
• Lymphocytes immunology   MeSH
• Pokeweed Mitogens pharmacology   MeSH
• Hot Temperature MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Formaldehyde MeSH
• Immunoglobulin Isotypes MeSH
• Pokeweed Mitogens MeSH