HEMOREGULATORY PEPTIDE (HP5B) DIMER EFFECTS ON NORMAL AND MALIGNANT-CELLS IN CULTURE

The dimer of the hemoregulatory peptide HP5b has been investigated for biological effects on various cell types in culture including mouse g ranulocyte-macrophage colony forming units (CFU-GM) from agar and muri ne long-term bone marrow culture (LTBMC). While CFU-GM were significan tly stimulated in both systems, mitogen activation of mouse T, B and n atural killer (NK) cells was not affected. Peptide treated mouse 3T3 f ibroblasts reached a higher saturation density than controls; otherwis e no effect was seen. A series of malignant cell lines was also tested . On a human glioblastoma cell line (GaMg) and rat glioma cell line (B T5C) a slight but significant stimulatory effect was found, while huma n mammary carcinoma cells (MCF7) were not affected. On SC1 mouse lymph oma cells a slight stimulation of cell growth was seen during the firs t part of exponential growth. Since HP5b acts as a stimulator for stro mal cell secretion of other growth factors, supernatants from a human bone marrow stromal cell line stimulated with HP5b were tested on vari ous cell lines. The effects of the supernatants on cell growth of the tested cell lines were not affected by HP5b treatment. Taken together with available in vivo data, the results indicate that the hemoregulat ory peptide is a selective stimulator of myelopoiesis.