Proliferative activity and subpopulation pattern of cells in murine thymus and spleen on the model of graft-versus-host chronic reaction under various diurnal regimens of IL-2 administration.

We studied the effects of IL-2 administration at different times of day to female B6D2F1 mice with experimental immunopathology, graft-versus-host chronic reaction induced by the administration of lymphoid cells from parental female DBA/2 mice. Recombinant murine IL-2 was injected subcutaneously at 10.00 (group 1) or 16.00 (group 2) after the first cell transfer. Evening administration of IL-2 in contrast to its morning injection prevented cell proliferation in the thymus and spleen, decreased the number of apoptotic splenocytes, significantly stimulated differentiation processes in the thymus, increased the amount of CD4 (+) 25 (high) thymocytes, and decreased the number of CD4 (+) 27 (low) splenocytes. These findings can serve as a prerequisite for the development of chronotherapeutic schemes for immunocorrection.

Structure of nuclear chromatin in cells of lymphoid organs and blood from mice maintained under abnormal light-dark cycle and treated with benz(a)pyrene.

We studied the effects of benzo(a)pyrene on lymphocyte chromatin in mice with experimental desynchronosis. Desynchronosis altered chromatin structure in immune system cells and suppressed the immune response. In mice with experimental desynchronosis, benzo(a)pyrene produced more pronounced changes in the chromatin structure compared to the control. It was inferred that light-dark cycle disturbances impair the resistance of organs and systems to damaging environmental factors.

The influence of experimental desynchronosis on the morphofunctional characteristics of mouse immune system.

The aim of this study is to investigate the influence of experimental desynchronosis on the immune system and estimate benzo[a]pyrene (BP) influence on the immune reactivity of mice under the condition of desyncronosis (DS) in comparison with intact organisms. Mice (CBA X C57BL)F1 were kept under constant light during two weeks and natural alternation of darkness and light (control group). Animals of the two groups received benzo[a]pyrene solution in olive oil. The existence of diurnal variation of cell populations of lymphoid organs and blood, humoral immune response to SRBC were revealed. Changes of diurnal dynamics of these parameters and decrease of humoral immune response to SRBC have been observed in animals kept under constant light in comparison with animals kept under standard light conditions. It is likely to indicate the development of internal DS. BP influenced the cellular composition and immune response of intact and DS animals in a different way. So, the changes of light regime lead to development of the internal DS of immune system that influenced its functional capacity and sensitivity to damaging effect of chemical ecological factor.

Diurnal dynamics of cytokine spectrum produced by immunocompetent cells of intact mice.

The production of cytokines by immunocompetent cells of intact mice was studied in various phases of the diurnal cycle. The ratio of produced cytokines was shown to differ in various phases of the diurnal cycle. The correlation between spontaneous production of various cytokines disappeared at 20:00, which reflects the development of physiological immunosuppression due to evening increase in physical activity of mice and corresponding changes in neuroendocrine status. Our results illustrate the existence of diurnal variations in intercellular interactions in the immune system. These data should be taken into account in the study of the mechanisms for cytokine immunoregulation and development of new schemes for cytokine immunocorrection.

Proliferative activity of cells in mouse thymus and spleen under different diurnal regimens of interleukin-2 administration.

Circadian variations in spontaneous and concanavalin A-stimulated proliferation of mouse thymocytes and splenocytes were studied after administration of recombinant interleukin-2 at different times of day. Differences were revealed in the effect of morning and evening treatment with the cytokine. The time of injection corresponded to various phases of the natural circadian rhythm of endogenous interleukin-2 production, which probably contributes to diurnal differences in the influence of this cytokine.