Purification and analysis of rat hematopoietic stem cells by flow cytometry.

The monoclonal antibody OX7 recognizes an epitope expressed on the Thy-1 glycoprotein, OX22 recognizes the high molecular weight form(s) on leukocyte common antigen, and W3/13 recognized determinants found on certain sialoglycoproteins. Recently, the rat colony-forming unit spleen (CFU-S) was characterized as being OX7 upper 20% positive (OX7u20%), OX22 negative (OX22-), and W3/13 weakly positive (W3/13+). In the present study these observations have been extended to include the hematopoietic stem cell (HSC).

Rat colony-forming unit spleen is OX7 positive, W3/13 positive, OX1 positive, and OX22 negative.

Using the monoclonal antibodies OX7 HL, W3/13 HLK, OX1 HLK, OX22, and the technique of fluorescence activated cell sorting, it was possible to characterize the phenotype of the rat marrow CFU-S as OX7 upper 20% positive, W3/13 lower 50% positive, OX1 positive, and OX22 negative. OX7 recognizes an antigenic determinant expressed on the Thy1 glycoprotein, W3/13 recognizes a determinant expressed on some sialoglycoproteins, OX1 recognizes all four apparent molecular weight forms of leukocyte common antigen, while OX22 recognizes only the high molecular weight forms of leukocyte common antigen. It was determined that the concentration of OX7 upper 20% positive, W3/13 lower 50% positive, OX1 positive, and OX22 negative cells in the marrow was 3085 +/- 1446/10(6) cells.

Presence of transforming growth factors in human breast cancer cells.

Conditioned medium (CM) from a human mammary carcinoma cell line, MCF-7, and ten individual clones derived from these cells was examined for the presence of transforming growth factors (TGFs). Concentrated CM from all of the MCF-7 cell lines was found to stimulate the anchorage-independent growth of normal rat kidney cells in soft agar and to inhibit the binding of epidermal growth factor (EGF) to mouse NIH/3T3 fibroblasts and to A431 human epidermoid carcinoma cell membranes. The soft agar stimulating activity was heat stable but sensitive to treatment with dithiothreitol.

Effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the growth inhibitory and increased phosphatidylinositol (PI) responses induced by epidermal growth factor (EGF) in A431 cells.

Epidermal growth factor (EGF) inhibited the growth of A431 human epidermoid carcinoma cells. The tumor promoting, phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) also retarded A431 cell growth. Addition of both TPA and EGF inhibited cell growth in an additive or synergistic manner depending upon the initial plating density of the cultures.