Number of stromal precursors in mouse bone marrow and expression of cytokine genes in primary cultures of mouse bone marrow cells during various periods after immunization with S. typhimurium antigens.

Administration of S. typhimurium microbial mass to mice was followed by a significant increase (by 3-4 times) in the efficiency of cloning and number of stromal precursors in the femoral bone marrow. These parameters were maximum on days 1-3, but returned to normal by the 8th-15th day after immunization. As differentiated from intact animals, the expression of genes for proinflammatory cytokines IL-1ß (day 1 after immunization), IL-6 (days 1-3), TNF-α (days 1, 3, and 6), and IFN-α (days 1-3) was detected in bone marrow cultures from immunized mice. The expression of genes for IFN-γ, IL-18, and IFN-α was decreased on days 1, 3, and 6 after immunization of animals, respectively. Gene expression for the anti-inflammatory cytokine IL-4 was observed on day 6 after immunization. Therefore, this system was not characterized by a decrease in the immune response of stromal cells. The stromal component of hemopoietic and lymphoid organs has the vector of influences in response to bacterial antigens. This vector is directed to the stimulation and progression, but not to the suppression of immune reactions. Our results indicate that resident stromal cells play a role in the immune response of the body.