functional and developmental analysis of cd4+cd25+ regulatory t cells under the influence of streptococcal m protein in rheumatic heart disease

the purpose of this study was to determine the role of streptococcal m protein in naturally-occurring cd4+cd25+ regulatory t cells (ntregs) function and development in rheumatic heart disease in iraqi patients. streptococcus pyogenes was isolated for subsequent m protein extraction. also, peripheral blood ntregs and cd4+ t cells were isolated by using magnetic cell separation system. tissue culture for isolated cells was performed in the presence and absence of m protein. cell count was performed, and tumor necrosis factor alpha (tnf-α) and interleukin-4 (il-4) were determined in culture supernatant using elisa system. there was a significant positive correlation (p 0.05), association (r=0.353) between the mean number of ntregs and cd4+ t cells in the presence of m protein. the m protein stimulated cd4+ t cells to produce il-4 in very little amount (<4 pg/ml) in all samples. compared to the production of il4, tnf-α was produced in higher concentrations in the culture supernatants. the findings of the study indicate that streptococcal m protein has an important role in increasing the proliferation of cd4+cd25+regulatory t cells and cd4+ t cells. however, cd4+cd25+ regulatory t cells have lower suppressive activity against cd4+ t cells in the presence of m protein.