INCREASE OF BOTH CIRCULATING TH1 AND TH2 T-LYMPHOCYTE SUBSETS IN IGA NEPHROPATHY

IgA nephropathy (IgAN), characterized by glomerular deposition of IgA and frequently elevated plasma IgA levels, has increased T helper cell activity. in vitro measurement of cytokines in supernatant of culture d peripheral lymphocytes revealed conflicting findings. We examined th e profile of cytokine mRNA expressed in purified CD4+ cells in patient s with IgAN in order to study their pattern of Th1 (releases IL-2 and interferon-gamma (IFN-gamma)) and Th2 (releases IL-4 and IL-5) T cell response. We assessed the circulating CD4+ T cells in patients and nor mal controls by the expression of messenger RNA (mRNA) for IL-2, IL-4, IL-5 and IFN-gamma. The cytokine mRNAs were analysed with reverse tra nscription-polymerase chain reaction and were measured semiquantitativ ely by using a housekeeping gene, beta-actin. Compared with the contro l subjects, CD4+ T lymphocytes from patients with IgAN expressed a hig her level of IL-2 mRNA (P=0.007), IFN-gamma mRNA (P = 0.04), IL-4 mRNA (P = 0.048), and IL-5 mRNA (P = 0.016). Within these patients with Ig AN, a good correlation was demonstrated between the gene expression of cytokines in Th 1 or Th2 cells. The IL-2 mRNA levels in Th1 cells fro m these patients with IgAN also correlated significantly with the IL-4 or IL-5 mRNA levels in their Th2 cells. Our study revealed IgAN is as sociated with activation in circulating lymphocytes of the IL-2, IFN-7 , IL-4 and IL-5 gene cluster, a pattern compatible with activation of both the Th1- and Th2-like T lymphocyte population. The increased tran scription of these cytokine genes may be contributory to the immunopat hologic findings in IgAN.