We inferred that in the pathogenesis of GPA/MPA, rapamycin may predominantly affect mTORC2 compared to mTORC1 in CD4+IL-4+ T cells and thus may suppress CD4+IL-4+ T cell activation and differentiation by interfering with the inhibitory effect of SOCS5 on STAT6 signalling. Here, CD4 is linked to granulomatosis with polyangiitis.