Ethnic disparities in outcome from posttransplant infections.

Black transplant recipients have decreased graft survival and increased rejection rates compared with whites. Because increased rejection rates may lead to more immunosuppression in black recipients, ethnic differences may exist for outcomes of posttransplant infectious complications. All episodes of infection between December 1996 and October 1998 on the transplant services at the University of Virginia Health Sciences Center were prospectively evaluated. Parameters recorded included self-designated ethnicity, demographics, APACHE II scores, laboratory and microbiologic data, immunosuppression, episodes of rejection, and outcome measures. Evaluation of 303 episodes of infection demonstrated an increased mortality rate for white compared with black recipients (19% vs. 3%, P = 0.0006) despite having a similar severity of illness (APACHE II score). Among renal transplant recipients, episodes of infection occurring in black recipients (n = 46) were also associated with a decreased mortality rate versus whites (n = 89) (0% vs. 15%, P = 0.006) and shorter mean length of stay (12 +/- 2 vs. 25 +/- 4 days, P = 0.002) despite similar severity of illness and rejection rates. For posttransplant infections in liver transplant recipients, blacks (n = 23) demonstrated a trend toward decreased mortality (9% vs. 26%, P = 0.07) but equal lengths of stay despite similar APACHE II scores, rejection rates, and age. White liver transplant recipients had an increased incidence of viral infections (15% vs. 0%, P = 0.03). All other infecting organisms were similar. The unexpected finding of a significantly decreased rate of mortality associated with posttransplant infections in black recipients remains largely unexplained but may be related to subtle differences in immune response between racial or ethnic groups.

Improved specificity and sensitivity when using pronase-digested lymphocytes to perform flow-cytometric crossmatch prior to renal transplantation.

Several laboratories have resorted to flow-cytometric crossmatch (FCXM) in an effort to prevent hyperacute and accelerated renal allograft rejections. The currently employed FCXM has problems with both false-positive and -negative reactions, largely as a result of irrelevant IgG binding to Fc IgG receptors. In 1980, we circumvented this problem by digesting Fc IgG receptors with pronase, and demonstrated that, with immunofluorescence microscopy (IF), detection of IgG anti-HLA antibodies was highly sensitive and specific. In 1995, we introduced the pronase technique to FCXM and showed that this enzyme did not decrease HLA expression. We present herein a prospective study at our institution to determine whether FCXM using pronase-digested (PD) lymphocytes is as sensitive and more specific than FCXM with undigested (UD) lymphocytes when compared with the highly sensitive and specific IF assay. In analyzing the 186 donor-specific pre-renal-transplant crossmatches, we found that PD FCXM was as sensitive and specific as IF and was able to detect weak IgG anti-HLA antibodies that bound to B cells. Fourteen of these patients would have been denied transplants if one were to have relied on UD FCXM. The data clearly indicate that PD FCXM can reliably be used to detect weak IgG anti-HLA antibodies before renal transplantation.