CD40LG and membranoproliferative glomerulonephritis: The differences in renal injury among various types of cryoglobulinemia are determined by the composition of immune complexes and the degree of complement activation: Type I shows direct monoclonal immunoglobulin deposition with minimal inflammation; Type II involves monoclonal IgM-polyclonal IgG complexes causing strong complement activation and membranoproliferative glomerulonephritis; Type III features polyclonal immune complexes producing milder mesangioproliferative lesions (2, 50, 51).