No abstract

We studied molecular mechanisms of immunoprotective effects of two dipeptides, AB-O and R-1, on cultured human and rat thymic cells. Both dipeptides were shown to increase the expression of lymphocyte differentiation marker CD5 in thymic cells. Dipeptide AB-O induced T-cells precursor differentiation towards CD4(+)T-helpers and its effect was weaker than that of dipeptide R-1. Dipeptide R-1 stimulates differentiation of CD5(+) cells to mature T-helpers and cytotoxic CD8(+) T cells and hence can be considered as a bioactive substance possessing immunomodulator and antiallergic activity.

A population of neuroendocrine cells secreting chromogranin A was verified in the intestine of subjects aged over 60 years. The count of intestinal cells expressing chromogranin A and Ki-67 proliferation protein increases with aging. More intensive expression of chromogranin A and Ki-67 protein in senile age and in long-livers is presumably a compensatory mechanism aimed at the gastrointestinal function maintenance during its age-associated involution.