Isolation and characterization of HL-A variants in cultured human lymphoid cells.

We have developed a procedure for immune selection in an established human lymphoid cell line based on HL-A, the major human histocompatibility locus. After a single brief exposure to selective conditions, HL-A2 variant clones were isolated from an HL-A2/HL-A3 heterozygous line. The variant clones occurred at a frequency of about 1 x 10(-6). The variant phenotype was stable during prolonged growth in the absence of antiserum after isolation. The variant sublines bound [unk] 1/1000 the HL-A2 antibody per cell as the parent line. Variation was specific in that expression of antigens not selected against was unimpaired. Loss of the chromosome bearing HL-A2 was excluded as the cause of variation because the variants, like the parent line, were heterozygous for phosphoglucomutase (EC 2.7.5.1) determined by structural locus PGM(3), which is linked to HL-A.