[The biological activity of chalone-like proteoglycans isolated from the spleen and thymus at various periods of ontogeny].

Chalone-like proteoglycans from sheep and bovine thymus and spleen were shown to suppress cell proliferation in murine thymus or spleen. Their effect appeared to be organ-specific but not species-specific. Administration of the proteoglycans resulted in a decrease in the mitotic activity of thymus and spleen cells 24h (strain C57BL), three days (hybrids), four days (nude mice) or five days (highly cancerous strain C3H/He and white mongrel mice) after birth. These changes are probably due to genetic peculiarities of immune system formation in different mouse strains. The activity of chalone-like proteoglycans from spleen and thymus of 1-, 3- and 6-months old sheep was lower than that of adult sheep (two and five years old) indicating that the proteoglycan activity increases during ontogenesis.