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The glycosaminoglycans (GAG) are the major constituents of placenta connective tissue. The analysis of the proteoglycan extracted from placenta confirmed the presence of chondroitin sulfate which consist of various proportions of both 4-sulfated and 6-sulfated disaccharide repeats. To investigate the activity of placenta chondroitin sulfates regulating the function of immune-related cells, we examined their effects on responsiveness of splenocytes to mitogens such as ConA and LPS. Chondroitin sulfate fractions eluted with 0.2M and 2.0M, but not 0.5M, NaCl suppressed the proliferation of splenocytes in a dose-dependent manner. When the cultures were co-incubated with T-cell mitogen, Con A, both 0.2M- and 2.0M-eluted chondroitin sulfate fractions also markedly suppressed the proliferation of splenocytes, indicating that the chondroitin sulfate fractions play a role in down-regulation of T cell activation. In contrast, in an experiment that B-cell mitogen, LPS, was added to the cultures, these chondroitin sulfates (0.2M- and 2.0M-eluted fractions) showed just a slight effect on LPS-stimulated splenocytes. Interestingly, 0.5M-eluted chondroitin sulfate fraction had no effect on the proliferation of both ConA- and LPS-stimulated. Taken together, it suggests that human placenta contains chondroitin sulfates which are effective for regulation of immune-related cells, and those proteoglycans from human placenta with 0.2M as well as 2.0M NaCl are responsible for the immuno-regulatory effect, especially down-regulation of ConA-stimulated T-lymphocytes. This paper reports the presence of chondroitin sulfate from the human placenta and its suppression activity of the function of immune-related cells.
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