A screening assay to simultaneously determine the presence and specificity of HLA anti-idiotypic antibodies.

HLA sensitization is generally associated with an increased risk of graft failure. However, in many cases, highly sensitized patients with a negative current serum crossmatch may be successfully transplanted despite the high levels of alloantibodies (Ab1) in their serum. Sensitized patients may be divided into two groups. The group with a high-risk of early graft failure produces a negative current serum crossmatch as a result of antibody attrition, but upon transplantation the reactivation of Ab1 by the donor organ results in graft failure. The low-risk group gives a negative current serum crossmatch due to the abrogation of Ab1 by anti-idiotypic antibodies (Ab2). This specific inhibition results in the protection of the graft and improved graft survival. In this paper we describe a screening method which enables large numbers of patients to be assessed for the presence of Ab2 in pretransplant sera, while simultaneously determining the specificities of these antibodies. The pretransplant assessment of sensitized patients for the presence of Ab2 would enable low-risk patients to be distinguished from high-risk patients, while information regarding Ab2 specificity would enable permissible mismatches to be considered. With this information at hand, the pretransplant waiting time for these patients may be greatly reduced. In our modification of the inhibition assay, selected dilutions of peak sera (P/n) were tested in the presence of either platelet absorbed current serum (P/n + Cabs) or an equal volume of fetal calf serum (P/n + FCS) as a dilution control.(ABSTRACT TRUNCATED AT 250 WORDS)