Cell surface antigens reacting with antiretrovirus sera on normal mouse spleen cells: a flow cytometric study

The development of erythroleukemia in Balb/c mice injected with Rauscher leukemia virus has been followed by indirect immunofluorescence technique and flow cytometry, using antiserum against disrupted of virions. The progression of the disease was accompanied by a great increase in the number of large, immunofluorescence positive cells. A subpopulation of normal spleen cells was also highly positive. The expression of the antigens in normal cells was examined in relation to the cell cycle. The majority of the S-G2/M phase cells were found in the antigen positive compartment of larger cells. A two-color analysis of immunofluorescence and DNA content revealed that the distribution of antigen expression in G1 phase was broad, gradually decreasing from a low-intensity mode. The cell with double DNA content distributed evenly around a modus of five-fold higher intensity. In experiments with stimulated bone-marrow cells, superiority of S-phase cells in anti-Rauscher serum binding was found. Cell-surface gp70 antigen is suggested to be involved in this cell-cycle dependent binding of antibodies by normal cells.