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 5×10 3 to 50×10 3 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.