Cold-reacting IgM antibody-induced renal allograft failure. Similarity to hyperacute rejection

Hyperacute rejection of renal allografts is usually mediated by IgG antibody, but recent studies indicate that cold-reacting IgM alloantibodies are also associated with immediate malfunction of renal allografts. We report 2 cases of cold-reacting IgM-mediated allograft malfunction in which immediate posttransplant biopsies resembled hyperacute rejection. This reaction can probably be prevented by warming the kidney just before transplantation.