The detection by enzyme-linked immunosorbent assays of non-complement-fixing HLA antibodies in transfusion medicine

Noncomplement-fixing white cell antibodies have been demonstrated by the use of immunofluorescence flow cytometry against intact lymphocytes. However, such antibodies may be either HLA-specific or directed against other white cell antigens. Commercial enzyme-linked immunosorbent assay (ELISA) kits, using solubilized HLA molecules as targets, enable such HLA-specific antibodies to be detected in patients who are refractory to platelet transfusion, patients experiencing febrile transfusion reactions, and patients whose sera give nonspecific hemagglutination in indirect antiglobulin tests.

Sera from all three groups of patients, previously screened for cytotoxic antibodies by using complement-dependent lymphocytotoxicity, were re-investigated with commercial ELISA kits for HLA antibody screening and identification using the manufacturers' recommended test methods.

Non-complement fixing HLA antibodies were detected by ELISA in many sera that were lymphocytotoxicity test-negative; that is, 14 (17.5%) of 80 from refractory patients, 8 (23.5%) of 34 from those with febrile reactions, and 11 (22.4%) of 49 from those with nonspecific hemagglutination in the direct antiglobulin test. However, not all cytotoxic white cell antibodies were detectable by ELISA: only 19 (82.6%) of 23, 19 (67.8%) of 28, and 11 (73.6%) of 49, respectively in the three groups. Similarly, only 143 (79.4%) of 181 cytotoxic sera with clear-cut HLA-A or -B locus specificities were detectable by ELISA.

ELISAs detect some but not all clinically significant HLA antibodies, irrespective of their ability to fix complement in vitro.