CD4 and rheumatoid arthritis: Megamonas abundance has also been associated with elevated serum levels of IL-10, IL-2, IL-4, TNF-a, and IFN-g, as well as with the Th1 and Th2 CD4+ T-cell subpopulation in RA patients [36], and with markers of disease either in iSLE [38] and in pSS [39].