Effect of immunization with polyvinylpyrrolidone on the counts of stromal precursor cells in bone marrow and spleen of CBA and CBA/N mice and cytokine gene expression in primary cultures of these cells.

Injection of polyvinylpyrrolidone (synthetic type 2 T-independent antigen) stimulated the efficiency of clone-forming efficiency and the content of stromal precursor cells in CBA mice in the femoral bone marrow (almost 3-fold) and in the spleen (by 1.7 times) with the peak within 24 h and normalization by day 3 after immunization. The expression of IL-6, IL-8, and TNF-α genes in bone marrow and spleen cultures from immunized animals appeared on day 1 and disappeared on day 3. Hence, stimulation of stromal tissue in response to polyvinylpyrrolidone immunization was significantly less pronounced in comparison with immunization with S. typhimurium antigens. The counts of stromal precursor cells in these organs did not increase in CBA/N mice not responding to polyvinylpyrrolidone because they had no xid-mutation in Brutton's tyrosine kinase (Btk) gene, and the proinflammatory cytokine genes expression in primary cultures derived from these animals did not increase either. These data indicated that the degree of stromal tissue stimulation in immunized mice correlated with the immune response intensity. This indicated a close relationship between the stromal tissue and immune system. Stromal tissue seemed to be stimulated not only and not so much through the stromal cell Toll-like receptors, but mainly through interactions of immunocompetent and stromal cells, the former presumably playing the leading role in this process.