Serological identification of Ia antigens: report of a British region Ia workshop.

In preparation for the 7th International Histocompatibility Workshop 13 laboratories in the British Region participated in a local workshop. One hundred and twenty-three sera which had been previously shown to have activity on either normal B cells, CLL cells or B cell lymphoid lines in the absence of HLA-A, B or C activity were exchanged between the laboratories. These sera were tested on a total of 212 B cells, 101 CLL cells, 76 T cells and 76 lymphoid cell lines. The data was collected and analyzed in Oxford. The analysis showed that six groups of sera could be distinguished. When these groups were compared with the D locus typing of some of the lymphoid lines which were derived from individuals used as MLC typing cells, they were seen to have significant associations with D locus antigens. The serological groups defined were therefore given numbers corresponding to the D locus numbers they associate with, i.e. UK1 is associated with DW1 and so on for UK2, 3, 4, 5 and 7. Comparison of typing techniques showed that long incubation both with antiserum and then with complement, 1 hour + 2 hours gave the best and most reproducible reactions on normal B cells. Residual anti-HLA-A, B or C activity in some of the sera even after platelet absorption showed the importance of adequate checking on T cells after absorption.