Modulating effects of calcium on immune response of homoiothermal animal under thermoneutral conditions and during deep cooling

Preliminary ionophoretic administration of Ca(2+) ions into the skin prevents the inhibitory effects of deep cooling on some processes characterizing the immune response. Differently directed changes in some immune response parameters induced by exogenous calcium and deep cooling suggest that competitive interactions between calcium-dependent processes can serve as mechanisms of functional changes in various physiological systems during the formation of the systemic reaction of a homoiothermal organism to cold.

Effect of rapid slight cooling of the skin in various phases of immunogenesis on the immune response

Slight cooling had no effect on heat emission and heat production, but modulated the immune response to antigen in animals. Changes in the immune response upon rapid slight cooling of the skin (by 1.5 degrees C) depended on the phase of immunogenesis corresponding to cold exposure. When cooling was performed immediately after immunization, antibody production increased in the spleen and blood, while antigen binding in the spleen remained unchanged. Cold exposure on day 5 after antigen treatment as well as immunization at the peak of cooling did not modulate antibody production, but increased antigen binding in the spleen. Our findings attest to an important role of the temperature factor in the formation of the immune response, which should be taken into account during vaccination.

[Effect of cold on the antigen binding function of splenic cells at different periods of immunogenesis in rats]

The patterns of changes in the immune response when deep cooling with different rates acted at various periods during development of the immune response, were examined in Wistar rats. Cold exposure causes not only a suppression but also stimulation of the immune response to antigen. The suppressive effect of deep cooling when it preceded immune challenge (the antigen injected at a body temperature decreased by 3-4 degrees C) waned and became stimulating with increasing time interval between antigen challenge and cold exposure. The stimulating effect on the immune response was most pronounced when cold exposure occurred in 5 days after the antigen challenge. These changes differed quantitatively also when cooling was either rapid, or slow. Thus the modulating effect of the thermal afferent signal was differently manifested depending in the cooling rate, i.e. the presence or absence of the dynamic activity of the peripheral thermosensitive afferents, and the time elapsed between antigen challenge and cold exposure.

Immune response and corticosteroid content in different regimens of cooling

The effects of different cooling regimens modulating thermal afferent signal on the immune response were experimentally studied on rats. Immunization at low body temperature changed the immune response to the antigen. These changes depended on the depth and rate of previous cooling. The presence of dynamic activity of peripheral thermosensitive afferents potentiated the immune response after surface cooling and reduced the degree of suppression of the immune response after deep cooling. No clear-cut relationship between changes in the immune response and blood concentration of corticosterone during cooling was found.

[Effect of cooling rate and intensity on the immune response and corticosterone blood level in rats]

Changes in the rat antigen-induced immune activity were shown to depend on cooling depth: slight cooling activated the immune response whereas deep cooling inhibited it. Involvement of the skin cold receptors' dynamic activity in responses to rapid cooling attenuated the effect of cold exposure on the immune response as well as the corticosterone elevation in plasma.

[The effect of interleukin-2 on rosette formation and its dependence on the serotonin level]

The analogy of the immunomodulating effects of the mediators of functionally coupled immune and serotoninergic systems was demonstrated in CBA mice immunized with sheep erythrocytes. Both agents in low doses stimulated and in high doses suppressed the response of the host to the antigen. Combined use of IL-2 and serotonin in optimal doses of similar action was shown to revert the effect into the opposite one. These data attest to the relationship of serotonin and IL-2 in the process of immunomodulation and to the importance of the balance of the substances in the environment at the moment of exposure to the antigenic information.

[Immunoregulatory properties of human recombinant angiogenin]

Rosette formation, hypersensibility of slow type and humoral reaction as an answer to immunization by ram erythrocytes in c conditions of normal and changed angiogenin level have been studied in CBA mice.

[ATP and serotonin in immunomodulation]

Such an aspect of interaction of serotonin with ATP as a process of immunomodulation have been shown. Obtained data lets assume the necessity of combined participation of serotonin and ATP when used in low concentrations, leading to stimulation of antigen reaction. The blocking function of ATP-serotonin complex with high optimal doses of both components, relative to immunosuppressive activity of both modulators has been established. The possible mechanisms of revealed processes are discussed.

[Ways of realizing the immunomodulating effects of mediators]

On the process of rosette formation in CBA mice spleens, immunized by ram erythrocytes, 1) participation of hypothalamohypophyseal complex in depressive effect of ATP (high doses), 2) participation of n. vagus in stimulating effects of serotonin and ATP (low doses), 3) participation of both regulating ways in analogue dose-dependent effects of recombinant human interleukin-2, have been shown.

[Effects of the interaction of serotonin with cells]

On the process of rosette-formation in CBA mice, biological effect of serotonin interaction with enriched T-lymphocytes by cells (ETLC), got from blood leukocytes and with peritoneal adhering cells (AC) has been studied. Participation of n. vagus in realization of serotonin-induced helper effect of ETLC and participation of hypothalamo-hypophysial-adrenal complex in realization of serotonin-induced suppressor effect of AC have been shown.

[Participation of the hypophysis in immunomodulation during interaction with monoaminergic systems]

The participation of the pituitary gland in the actualization of dopamine-dependent immune response after removal of adrenals and an increase in the serotonin content, was studied in the CBA mice. A lesion of the pituitary stalk prevented the activation of immune response usually observed in adrenalectomized animals treated with serotonin. The data obtained suggest that exclusion of the serotoninergic immunomodulating pathways out of the CNS causes the predominance of dopaminergic system. Activating action of the latter on the immunity is actualized via the hypophysis and subsequently maintained by central mechanisms.

[Mechanisms of realization of stimulating effects of serotonin on immune processes]

Low dosages of serotonin and 5-hydroxytryptophan were found to stimulate rosette-forming process in spleens of male CBA mice (5 X 10(6)) immunized with sheep red blood cells, in contrast to high dosages that are known to induce inhibition. The above finding suggests a bimodality of serotoninergic immunomodulation. Immune responses were compared between shamoperated, adrenalectomized, thymectomized mice and mice with lesion of hypothalamo-pituitary complex (the destruction of pituitary or its stalk). It was shown, that neither hypothalamo-pituitary-adrenal system by means of which the inhibitory effect of serotonin (high dose) was released, no thymus, where the increase of rosette-forming process was released in adrenalectomized mice which obtained high doses of serotonin. The dosage-response curve suggests mediating of opposite serotonin effects via serotonin reactive structures with different serotonin sensitivity.

[Characteristics of serotonin binding by the cells of immunocompetent tissues and synaptosomes]

The ratio of surface and intracellular serotonin binding by the cells of immunocompetent tissues and synaptosomes of immunized and intact CBA mice was studied by treatment with imipramine inhibiting serotonin penetration through the cytoplasmic membrane. As early as 5 minutes after the antigen injection the content of intracellular amine increased with changes in its binding by the cytoplasmic membrane. The probability of the functional interconnection between the reaction of immunocompetent tissues to the antigen and two forms of serotonin binding by the cells of these tissues is discussed.

[Serotonin binding by various populations of peritoneal cells and blood leukocytes from intact and thymectomized mice]

Specific activity of 3H-serotonin binding with adhesive cells, as well as with T-lymphocyte enriched cells and B-lymphocytes, obtained from peritoneal excudate and blood leucocytes of CBA mice was determined. The highest affinity to amine was established in peritoneal T2 cells and adhesive blood cells. Results of studying the action of imipramin and blocators of some known serotonin receptors on amine binding with the investigated cells allow a conclusion on structural differences of serotonin-binding centres located on T-lymphocyte enriched cells and B-lymphocytes depending of their localization. The reduction of serotonin binding by immunocytes during ageing processes with animals (particularly tymectomized) was revealed, and this is supposed to be correlated with changes of immunological reactivity with ageing. It is supposed that serotonin participates in cooperative interactions of immunocytes in blood and peritoneal cavity.

[Peculiarities of specific binding of serotonin by blood leukocytes, peritoneal cells and synaptosomes of mice]

The properties of serotonin-active sites were studied on peritoneal cells, blood leukocytes and synaptosomes of mice (CBA line). Treatment of cell suspensions with EDTA, ouabain, strophanthin, 2,4-dinitrophenol, dithiothreitol and trypsin demonstrated that serotonin binding by peritoneal cells and leukocytes depends on bivalent ions and K+, Na+-pump operation, requires energy and intact disulfide bonds and is determined by a protein structure. ATP and ADP were found to inhibit amine adsorption by peritoneal cells. These cells specifically bind ATP 10 times more intensively than leukocytes. The data obtained are suggestive of differences in the composition of serotonin-active structures of blood leukocytes, peritoneal cells and synaptosomes.

[Specific binding of serotonin by blood leukocytes and peritoneal cells in the mouse]

It was shown that blood leukocytes and peritoneal cells of mice specifically bind serotonin (5-hydroxytryptamine) in amounts which exceed manyfold its binding by the cells of thymus, lymphatic nodes, spleen, Peyer's patches and bone marrow. The nature of this binding suggests that peritoneal cells and blood leukocytes contain cell populations (apart from those already known ones) capable of binding and trapping of serotonin.