THE EXPRESSION OF SPECIFIC SURFACE-ANTIGEN OF SMOOTH-MUSCLE CELLS IS RELATED TO PROLIFERATION

Monoclonal antibody L1 has been obtained after immunization of BALB/c mice with long-term cultured smooth muscle cells (SMC) orginally isolated from rat aortic media. Antibody L1 recognizes only the surface antigen of cultured SMC and does not react with other cultured rat cell types. It has been shown that in primary culture of SMC the L1-positive cells appear on the 2nd to 3rd day and their proportion increases up to the 7th day up to 40% in DMEM supplemented with 10% of fetal calf serum (FCS), up to 25% in DMEM with 5% of rat whole-blood serum, but up to only 5% in DMEM with 5% rat plasma-derived serum. These results are in agreement with data on [14C]thymidine incorporation and on flow cytometry. Using FACS II, the SMC were sorted into subpopulations on the 4th and 8th days of primary culture according to the intensity of their specific immunofluorescence. It has been found that the DNA profile in intensively labelled cells corresponds to that in an intensively proliferating population of cells. These findings suggest that antigen L1 appears to be the specific marker of modulated SMC entering the cell cycle. © 1987.