High levels of serum IgM-ALA in transplant recipients are associated with better kidney allograft survival. Upper panels (before adding serum) depict B lymphocytes that normally express membrane IgM (FITC positive). The lower panels depict differences in the level of serum IgM bound to donor T lymphocytes (IgM-ALA) after addition of pretransplant serum from different ESRD patients. The difference in percentage of acute rejections and graft loss comparing high MCF versus the no and low MCF groups was statistically significant (P<0.02), as shown by the asterisks. MCF indicates increase in mean channel fluorescence of anti-IgM staining after addition of serum. Lobo PI, Schlegel KH, Spencer CE, Okusa MD, Chisholm C, Mchedlishvili N, et al.: Naturally occurring IgM anti-leukocyte autoantibodies (IgM-ALA) inhibit T-cell activation and chemotaxis. J. Immunol. 180:1780-1791, 2008. Copyright 2008. The American Association of Immunologists, Inc