Elevated B-cell autoantibodies among HIV+ transplant candidates: crossmatch implications

We report our experience in assessing autoantibodies among HIV+ patients considered for renal transplantation. Autoantibodies against autologous T and B cells were determined by complement-dependent cytotoxicity autocrossmatching (CDC) or flow cytometric autocrossmatching (FCXM) for 28 HIV+ and 72 HIV- men. T-cell CDC was negative among HIV+ and HIV- individuals (0%). In contrast, B-cell CDC was higher among HIV+ than HIV- patients (71% vs 4%, P = .001). However, HIV+ patients also showed unusual sensitivity to complement that potentially invalidated the B-cell CDC. Complement sensitivity was higher among those with positive versus negative HIV RNA (71% vs 25%, P < .01). Alternate use of FCXM showed equivalent T-cell FCXM between HIV+ versus HIV- individuals (5% vs 1%, P = NS). However, B-cell FCXM was more prevalent among HIV+ than HIV- patients (45% vs 2%, P < .01). B-cell FCXM was higher among patients with positive than negative HIV RNA (57% vs 25%, P < .05). Simulated allocrossmatching against unrelated DR-matched donors showed that two out of four HIV+ patients with positive FCXM had positive allocrossmatches that were eliminated when allocrossmatching was repeated using autoabsorbed serum. We conclude that HIV+ patients are more likely to produce B-cell autoantibodies than HIV- individuals, which, if not realized, could cause false-positive allocrossmatches and inappropriate transplant denial.