Two cell-surface markers for human chromosome 1 in interspecies hybrids.

Monoclonal antibodies AbAJ9 and AbT87 define two distinct human cell-surface antigen systems (1, 2). Both antibodies react with a wide variety of cultured human cell types but not with rodent cell lines. AbAJ9 identifies a glycoprotein of 140,000 mol wt and AbT87 identifies a glycoprotein of 60,000 mol wt. The genetic control of antigen expression was studied in rodent-human somatic cell hybrids containing different subsets of the entire human chromosome complement, using an immune rosetting assay for serological analysis and hybrid selection. The presence of human chromosome 1 was found to be both necessary and sufficient for expression of antigens AJ9 and T87 in hybrid cells. Two independent gene loci on chromosome 1, designated MSK -1 for AJ9 and MSK -2 for T87 , control the expression of these antigens. We have assigned MSK -1 to region 1 cen-p22 and MSK -2 to region 1q32 -qter, using hybrids containing only fragments of human chromosome 1.