Functional and Developmental Analysis of CD4+CD25+Regulatory T Cells Under the Influence of Streptococcal MProtein in Rheumatic Heart Disease


ABSTRUCT:BACKGROUND:CD4+CD25+ regulatory T cells are known to suppress the immune response in general, these cellswere studied in the presence of streptococcal M protein which has an important role in thepathogenesis of rheumatic heart disease.OBJECTIVE:The purpose of this study was to determine the role of streptococcal M protein in naturallyoccurring CD4+CD25+ regulatory T cells (nTregs) function and development in rheumatic heartdisease Iraqi patients.METHODS:Streptococcus pyogenes was isolated for subsequent M protein extraction. Also, peripheral bloodnTregs and CD4+ T cells were isolated by using Magnetic Cell Separation System (MACS). Tissueculture system for isolated cells was performed in the presence and absence of M proteinstimulation. Cell count was performed, also, TNF-α, and IL-4 were determined in culturesupernatant using ELISA system.RESULTS:It was found a highly significant positive association between the number of the cellularproliferation for both nTregs and CD4+ T cells with or without streptococcal M protein stimulationin isolated cell culture systems (p < 0.01), but, there found a highly significant negative correlationbetween the mean number of nTregs and CD4+ T cells in mixed culture system in the absence ofM protein (r = -0.995). whereas, in the presence of M protein, there was a positive non-significantassociation between the mean number of both nTregs and CD4+ T cells (r = 0.353) (p > 0.05).Results obtained from ELISA test revealed that M protein-stimulated CD4+ T cells produced IL-4in very little amounts (< 4 pg/ml) in all cultures of samples and there was no significant differenceamong them. Whereas, TNF-α was produced in higher concentrations in the culture supernatantswhen compared with IL-4.CONCLUSION:Streptococcal M protein has an important role in increasing the proliferation of both CD4+CD25+regulatory T cells and CD4+ T cells, but the newer generation of CD4+CD25+ regulatory T cells inthe presence of M protein has lower suppressive activity against CD4+ T cells.