Immunopotentiation on murine spleen lymphocytes induced by polysaccharide fraction of Panax ginseng via upregulating calcineurin activity.

Calcineurin (CN), a unique Ca2+/calmodulin (CaM)-dependent serine/threonine protein phosphatase, plays a pivotal role in the activation and proliferation of T lymphocytes. Based on the effective molecular screening model established in our laboratory, we found that a part of polysaccharides from the stem and leaves of Panax ginseng, termed PGP-SL, could activate CN activity. Subsequently, we investigated whether PGP-SL also has immunological competence on murine spleen lymphocytes.

Kaempferol: a new immunosuppressant of calcineurin.

Calcineurin (CN), the Ca(2+)/calmodulin (CaM)-dependant protein phosphatase, is the target for immunosuppressive drugs cyclosporine A (CsA) and FK506. These immunosuppressants can inhibit CN activity after binding with respective immunophilins. Based on the model of screening by using p-nitrophenyl phosphate as a substrate for preliminary screening and (32)P-labeled 19-residue phosphopeptide as a specific substrate for final determination, we found Kaempferol, a natural flavonol, could inhibit CN activity in purified enzyme and Jurkat T-cells.