Dose-dependent effects of dexamethasone on activation and proliferation of donor immune memory T cells (CD45RO(+)) were studied. Activation of memory T cells associated with IL-2 production and membrane expression of CD25 molecule was resistant to dexamethasone. Proliferative activity of memory T cells associated with membrane expression of CD71 molecule was highly sensitive to dexamethasone. Hence, glucocorticoid hormones can maintain the clonal balance in the lymphoid tissue without preventing realization of the immune memory mechanism.

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Glucocorticoids are anti inflammatory and immunosuppressive agents with pleiotropic effects on the growth, differentiation, and functional activity of T lymphocytes. The comprehensive assessment of the influence of dexamethasone on the functional activity of T cells with different grades of differentiation was performed under experimental in vitro conditions. We established that dexamethasone suppressed the func tional activity of CD45RA + and CD45RO + T lymphocytes. In the population of naive (CD45RA + ) T cells, the inhibitory effect of dexamethasone on the early activation stages (IL 2 dependent, associated with the CD25 expression and IL 2 production) was more significant, whereas in the culture of primed memory cells (CD45RO + ), dexamethasone affects the later stages (IL 2 independent, associated with the expression of proliferation molecule CD71). Multidirectional effects of dexamethasone on the level of expression of mRNA of telomerase catalytic unit (hTERT) were associated with the degree of T cells differentiation. Most likely, the role of glucocorticoid hormones in immunogenesis is mainly the suppression of the excessive growth of T cells and the maintenance of the clonal balance in lymphoid tissue. CELL MOLECULAR BIOLOGYAbbreviations: Ac/Exp, T Cell Activation/Expansion Kit human; CD, cluster of differentiation; IL 2, interleukin 2; IL 2R, interleu kin 2 receptor; hTERT, human telomerase reverse transcriptase.

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Резюме. В настоящем обзоре предпринята попытка систематизировать существующие представления о наиболее значимых поверхностных антигенах иммунокомпетентных клеток и оценить их роль в процессах клеточного гомеостаза и формировании патологии.