Regulatory B Cells: An Exciting Target for Future Therapeutics in Transplantation

Renal allograft survival has increased tremendously over past decades; this has been mostly attributed to improvements in first-year survival. This report describes the evolution of renal allograft survival in the United States where a total of 252 910 patients received a single-organ kidney transplant between 1989 and 2009. Half-lives were obtained from the Kaplan-Meier and Cox models. Graft half-life for deceased-donor transplants was 6.6 years in 1989, increased to 8 years in 1995, then after the year 2000 further increased to 8.8 years by 2005. More significant improvements were made in higher risk transplants like ECD recipients where the half-lives increased from 3 years in 1989 to 6.4 years in 2005. In low-risk populations like living-donor-recipients half-life did not change with 11.4 years in 1989 and 11.9 years in 2005. First-year attrition rates show dramatic improvements across all subgroups; however, attrition rates beyond the first year show only small improvements and are somewhat more evident in black recipients. The significant progress that has occurred over the last two decades in renal transplantation is mostly driven by improvements in short-term graft survival but long-term attrition is slowly improving and could lead to bigger advances in the future. ©2010 The Authors Journal compilation©2010 The American Society of Transplantation and the American Society of Transplant Surgeons.

Experimental autoimmune encephalomyelitis (EAE) is an animal model for autoimmune central nervous system disease mediated by CD4 T cells. To examine the role of B cells in the induction of EAE, we used B10.PL (I-Au) mice rendered deficient in B cells by deletion of their μ chain transmembrane region (B10.PLμMT). By immunizing B10.PL and B10.PLμMT mice with the NH-terminal myelin basic protein encephalitogenic peptide Ac1-11, we observed no difference in the onset or severity of disease in the absence of mature B cells. There was, however, a greater variation in disease onset, severity, and especially of recovery in the B cell–deficient mice compared to controls. B10.PLμMT mice rarely returned to normal in the absence of B cells. Taken together, our data suggest that B cells do not play a role in the activation of encephalitogenic T cells, but may contribute to the immune modulation of acute EAE. The mechanisms to explain these effects are discussed.

The causes and clinical course of acute rejection vary, and it is not possible to predict graft outcome reliably on the basis of available clinical, pathological, and genetic markers. We hypothesized that previously unrecognized molecular heterogeneity might underlie some of the variability in the clinical course of acute renal allograft rejection and in its response to treatment. We used DNA microarrays in a systematic study of gene-expression patterns in biopsy samples from normal and dysfunctional renal allografts. A combination of exploratory and supervised bioinformatic methods was used to analyze these profiles. We found consistent differences among the gene-expression patterns associated with acute rejection, nephrotoxic effects of drugs, chronic allograft nephropathy, and normal kidneys. The gene-expression patterns associated with acute rejection suggested at least three possible distinct subtypes of acute rejection that, although indistinguishable by light microscopy, were marked by differences in immune activation and cellular proliferation. Since the gene-expression patterns pointed to substantial variation in the composition of immune infiltrates, we used immunohistochemical staining to define these subtypes further. This analysis revealed a striking association between dense CD20+ B-cell infiltrates and both clinical glucocorticoid resistance (P=0.01) and graft loss (P<0.001). Systematic analysis of gene-expression patterns provides a window on the biology and pathogenesis of renal allograft rejection. Biopsy samples from patients with acute rejection that are indistinguishable on conventional histologic analysis reveal extensive differences in gene expression, which are associated with differences in immunologic and cellular features and clinical course. The presence of dense clusters of B cells in a biopsy sample was strongly associated with severe graft rejection, suggesting a pivotal role of infiltrating B cells in acute rejection. Copyright 2003 Massachusetts Medical Society