Comparison of HL-A typing with NIH trays and the NIH technique with typing by the fluorochromasia cytotoxicity assay.

A comparison of HL-A phenotypes determined with plates containing predispensed typing sera supplied by the NIH Serum Bank with phenotypes determined by the fluorochromasia cytotoxicity assay using local reagents showed that the NIH plates (as dispensed in 1972) had an insufficient number and variety of typing sera. Using NIH trays, it was difficult to detect HL-A9 and W19, both of which specificities are now known to have subtypes. The NIH trays also appeared to detect more HL-A antigens than were consistent with the current theory of two segregant series, each expressing a maximum of two antigens. The excess antigens could not be comparatively evaluated in view of the small number of sera defining each. With the NIH technique, it was impossible to interpret the reactions if the preparation had too many dead cells. A high proportion of dead cells was occasionally noted when lymphocytes had been previously frozen or obtained from lymph nodes. When the NIH and fluorochromasia techniques were compared using the same antisera and fresh lymphocytes, they proved equivalent in sensitivity.