B-lymphocyte typing (HLA-DR, MT, MB) interlaboratory reproducibility

Frozen lymphocytes from six persons were shipped, in three batches, from one location to 11 other participating laboratories for B-lymphocyte typing. The cells were received by the participating laboratories in a frozen state with one exception. Four of the 12 (including the host laboratory) used two-color fluorescence method, seven used nylon wool to isolate B-lymphocytes followed by cytotoxicity testing using trypan blue, and one laboratory used goat anti-human F(ab')₂ to isolate B-lymphocytes for two cells and two-color fluorescence method for the other four cells. Reference antigen assignments of the various cells were essentially the consensus of the various laboratories and major departures from those assignments were considered errors. Twelve typing errors were seen in a total of 67 typings (for HLA-DR), i.e., an error rate of 17.9%. Four of the errors might have been due to the poor state of cells resulting from the participating laboratory storing the cells for over four weeks before testing. Six of the 12 laboratories were in agreement for all six cells and made no errors. Typing for MT antigens did not appear to be particularly reliable, but there was a good interlaboratory correlation for MB antigen assignments. The exercise has established the feasibility of conducting a cell exchange for B-lymphocyte typing over a fairly wide geographic area, and has shown that the overall error rate for HLA-DR antigen assignments is about three times the rate of HLA-AB typing.