The Combined Role of Galactose-Deficient IgA1 and Streptococcal IgA-Binding M Protein in Inducing IL-6 and C3 Secretion from Human Mesangial Cells: Implications for IgA Nephropathy.
IgA nephropathy (IgAN) is characterized by mesangial cell proliferation and extracellular matrix expansion associated with immune deposits consisting of galactose-deficient polymeric IgA1 and C3. We have previously shown that IgA-binding regions of streptococcal M proteins colocalize with IgA in mesangial immune deposits in patients with IgAN. In the present study, the IgA-binding M4 protein from