Monoclonal anti-actin antibody modulates expression of surface antigen on L cells

Monoclonal anti-actin antibody which is known to stimulate DNA synthesis and cell growth in a murine transformed cell line, L cell, was examined for its ability to modulate the expression of surface antigen on the cell membrane. There was a time dependent increase in the number of cell surface antigen molecules on L cells stimulated by monoclonal anti-actin antibody as measured by indirect immunofluorescence and flow cytometry. For L cells incubated for 12, 24, 48, 72, and 96 hours with monoclonal anti-actin antibody versus a myeloma control supernatant, the percentage of cells exhibiting high intensity immunofluorescence was 29 vs. 13, 13 vs. 10, 34 vs. 1, 52 vs. 11, and 35 vs. 18, respectively. We conclude that monoclonal anti-actin antibody modulates the time dependent surface expression of actin on L cells. It is likely that this modulated expression of surface actin-like molecules plays an important role in the transmission of stimulatory signals to the cells which result in enhanced cellular metabolism and proliferation.