Studies on endometrial cells in human pregnancy by monoclonal antibodies

Abstract By immunizing mice with endometrial cells from pregnant women, we obtained two hybridoma clones, 9D3 (IgG 1 ) and 9E3 (IgG 3 ), secreting monoclonal antibodies (MoAbs) that selectively stained endometrial stromal cells having prolactin in their cytoplasm, but did not stain glandular epithelium nor small lymphoid cells. From examination of tissues, cells and cell lines, it was found that 9E3 antigen was broadly distributed among various mesenchymal cells, while 9D3 antigen was distributed on a more restricted spectrum of mesenchymal cells, skin basal cells and a promonocytic cell line (U937). Neither of these antibodies stained peripheral blood cells, bone marrow cells or endometrium of the proliferating phase. Furthermore, 9D3 MoAb reacted with all melanoma cell lines and squamous cell lines examined. The antigenic molecule that was recognized by 9D3 MoAb had a molecular weight of 94,000.