[Analysis of rat hemopoietic cells using monoclonal antibodies]

Rat hemopoietic cells were analyzed with immunohistochemical technique, binding inhibition assay and flow cytometer using a monoclonal antibody (UB-12) to rat fetal liver hemopoietic cells. UB-12 positive cells were recognized in only red pulp but not in white pulp of spleen. The number and fluorescence intensity of UB-12 positive cells in spleen appeared to reach to peak at 6 weeks old occupying about 60 to 70% of total cells in red pulp. On the other hand, OX-7 (anti-Thy-1) positive and W3/13 (anti-leuko-sialoglycoprotein) positive cells were found in both red and white pulp, but not in marginal zone of spleen. UB-12 antigen was found on the surface of the cells only in the early stages of hemopoiesis: relatively large nuclei of UB-12 positive cells were rich in heterochromatin. There were a large number of free-ribosomes and some mitochondria in cytoplasm, and a centriole was observed in cytoplasm at some sections of UB-12 positive cells. From the EPICS analysis of adult rat bone marrow cells using UB-12, OX-7 and W3/13 monoclonal antibodies, the percent of UB-12, OX-7 and W3/13 positive cells was 82%, i.e., 18% was negative from these monoclonal antibodies. UB-12 single positive, OX-7 single positive and W3/13 single positive cells were 7%, 7% and 47%, respectively. The percent of triple positive cells with these antibodies was about 2%.