SELECTIVE EXPRESSION OF LY-6G ON MYELOID LINEAGE CELLS IN MOUSE BONE-MARROW - RB6-8C5 MAB TO GRANULOCYTE-DIFFERENTIATION ANTIGEN (GR-1) DETECTS MEMBERS OF THE LY-6 FAMILY

Mouse Ly-6 proteins are characterized by lineage-restricted patterns o f expression on lymphoid cells. A mAb (1A8) was produced to Ly-6G, a n ewly described member of the Ly-6 locus. Based on selective reactivity to cloned Ly-6 gene products expressed in EL4J cells, 1A8 was determi ned to be specific for Ly-6G. Furthermore, mAb to other Ly-6 specifici ties did not bind to Ly-6G-transfected EL4J cells, indicating that Ly- 6G is distinct from other serologically defined Ly-6 specificities. FA CS analysis using 1A8 demonstrated that Ly-6G was expressed in bone ma rrow but not substantially on other lymphoid tissues, including activa ted T and B cells. In the bone marrow, Ly-6G expression was primarily restricted to the cells with more forward angle light scatter, which a re mostly granulocytes. The RB6-8C5 mAb, previously described to detec t a myeloid-restricted Ag (Gr-1) on more differentiated granulocytes, also reacted with Ly-6G- and Ly-6C-transfected EL4J cells. Both 1A8 an d RB6-8C5 selectively precipitate a M(r) 21 to 25 kDa, glycosylphospha tidylinositol-anchored protein. Collectively, these data indicate that the Gr-1 Ag is a member of the Ly-6 family and further link expressio n of individual Ly-6 genes with distinct lineages in mouse bone marrow cells.