Dose-Dependent Effect of Bacillus sp. Metabolites from Permafrost on Lymphocyte Differentiation in the Thymus.

We studied the effect of a single intraperitoneal injection of metabolites from Bacillus sp. M3 strain isolated from permafrost (from 5×103 to 50×103 microbial bodies) on differentiation of T cells in the thymus of F1(CBA/Black-6) mice. On day 21 after the injection of metabolites, a dose-dependent decrease in the level of CD34+CD44+ and an increase in the number of CD34+CD44-, CD25-TCR+, CD25+TCR+max, CD4+CD8-, CD4-CD8+, and CD44+TCR+ lymphocytes were observed in the thymus. The increase in thymus level of mature (CD25+TCR+max) and migration-ready (CD44+TCR+) T cells in combination with a moderate decrease in the level of T cell precursors entering the thymus from the bone marrow (CD34+CD44+) can indicate a modulating influence of Bacillus sp. metabolites on functional activity of the thymus aimed at maintenance of the T cell balance in the body.