Expression of Murine Gamma Fetal Antigen in Adult Hematopoietic Tissue and During Induced Differentiation of Friend Erythroleukemia Cells

Quantitative analysis of extracts of various normal adult CD-1 mouse tissues indicated that the serologica"y defined murine gamma fetal antigen (γ-FA) was expressed at high levels in hematopoietic tissue in general and in bone marrow (BM) in particular. Metabolic labeling of isolated BM cells indicated that the BM was a site of γ-FA synthesis in the adult animal. The size(s) of the antigen immunoprecipitated from labeled BM cells (35 and 27 kilodaltons) with anti-γ-FA serum correlated well with molecular weight estimates of fibrosarcoma-fetal mouse-associated γ-FA, as determined by molecular sieve chromatography. For ascertainment of the relationship between hematopoietic cell differentiation and γ-FA content, a multiparameter flow cytometric approach was used to evaluate γ-FA levels in Friend erythroleukemia (FL) cells as a function of growth state (blast or dimethyl sulfoxide-differentiated) and cell-cycle compartment. Differentiated G1-arrested FL cells (G10) possessed significantly lower γ-FA-associated immunofluorescence as compared to control cells in the G0-G1 substate. Remaining S- and G2 + M-phase cells in differentiated populations demonstrated an even greater reduction in γ-FA content relative to control cells in the corresponding cell-cycle phases. The available data support the tentative classification of γ-FA as a murine differentiation antigen.