Effect of T-activin on thymus involution in mice

The effect of T-activin on thymus involution in mice was studied. T-activin in a dose of 1.0 micrograms/mouse was injected into young male (CBA X C57BL)F1 mice weighing 24.0 +/- 2.0 g daily for 20 days. Morphometric analysis of the thymus was made 6 months after the treatment with T-activin was completed. It was found that T-activin induced the suppression of physiological involution of the thymus together with the enhancement of the processes of thymocyte transformation and proliferation.     

Cell proliferation in mouse tissues after thymectomy and the administration of T-activin

The epithelium of mouse cornea and lymph nodes was examined for DNA-synthetic and mitotic activity at different times after thymectomy and administration of T-activin, an active factor of the thymus. Thymectomy entails retardation of the rate of corneal epithelium regeneration, diminution in both tissues under study of the amplitude of oscillations in cell proliferation throughout the day. Administration to the animals of the immunoactive thymic factor T-activin makes the circadian rhythm of cell proliferation return to normal. It is assumed that T-activin raises the capacity of lymphocytes to interact with epithelial cells, which manifests itself in the enhancement of their mitotic activity.     

Study of the action of immunomodulator T-activin on electric properties of plasma membranes of thymus cells by the use of fluorescent probes

T-activin alters the electric properties of plasmatic membranes of the T-activin treated suspension of mouse (CBAX X057B1) F1 thymic cells. These alterations were registered by means of negative charged fluorescent probe l-anilino-naphthalene-8-sulfonate (ANS) and positive charged 4-(p-dimethylaminostyryl)-1-methylpyridinium (DSM) by measurement of their fluorescence in the individual thymic cell. Apparently, T-activin leads to depolarization of transmembrane potential on plasmatic membrane of thymic cells. It seems that action of T-activin is similar to the effect of polycations, which alter cells ionic streams during lymphocyte activation. However, there is a version, that T-activin acts like neuraminidase, but it is activity less expressed.     

Effect of T-activin on thymocyte reproduction and migration

Forty seven F1 (CBA X C57Bl) mice were used for quantitative morphologic examination of the thymus on 1, 5, 10 and 15 days after a single injection of 0.5 microgram T-activin, and injections of 0.1 microgram of T-activin once a day during 5 days. The number of transformed thymocytes and mitoses figures in cortex was found to be increased reaching a maximum at the 5th day as regards the magnitude and spreading. By the end of the research the number of transformed thymocytes and mitoses returned to initial values. There was a periodical (at the 5th and 10th days) 1 mm2 reduction in the number of thymocytes, an increase in the proportion of medullary thymocytes, reaching maximum at the 5th day, and a tendency towards the reduction of a relative area of the parenchyma. These indicators did not return to the initial values by the 15th days. However there was a tendency towards normalization. The conclusion is made about the stimulatory effect of T-activin on reproduction and migration of thymocytes.     

Change in immunological and biochemical parameters in germ-free animals in response to T-activin

The influence of immunoregulating humoral thymus factor T-activin (fraction AFT-6) on the activity of xenobiotic metabolism enzymes (EMX) and cellular-dependent cytotoxicity was investigated in germ-free guinea-pigs. Germ-free and conventional animals were injected 5 micrograms of T-activin intraperitoneally, on 3 successive days. The control animals were injected a physiologic saline. A day after the last injection the animals were killed, and EMX and K cell activity was measured. It was found that EMX activity in germ-free animals was decreased. T-activin stimulated cytochrome P-450, NADP-cytochrome-C-reductase, glutathione-S-transferase, benzopyrene hydroxylase and epoxyhydrase activity. In conventional animals the activity of these enzymes remained unchanged under the influence of T-activin. K-cell activity in germ-free animals was decreased, as compared to conventional guinea-pigs. Under the influence of T-activin the parameter increased and stood at about 70% of normal values.     

Effect of T-activin on peripheral immunity organs in intact and thymectomized mice

Morphometry of the spleen, axillary lymph nodes and cytological assay of the bone marrow and peripheral blood were performed in (CBA X C57BL)F1 mice 1, 5, 10 and 15 days after subcutaneous injection of 0.5 microgram T-activin to intact and thymectomized (when adult) mice 2 months after operation. It was demonstrated that in intact animals, injection of T-activin stimulated the whole system of immunogenesis. The time course of plasmatization and the response of the germinative centers differing from that seen during antigen administration suggests that T-activin is not immunogenous, acting as a stimulant of the previous immune responses. The permanent amount of the degenerating cells attests to the lack of the toxic drug effect.     

Action of T-activin on human natural killer activity in vitro

The activity of natural killers (NK) from human peripheral blood was determined by 3H-uridine test using target cells K-562. T-activin effect on the activity of human NK in vitro depended on two parameters: the preparation dose and effector/target cells ratio. The inhibitory effect of T-activin was observed with high doses and increased E/T ratio, while the activating effect was noted with low doses and reduced E/T ratio. This can be attributed to the heterogeneity of NK population, different functional role of high and low doses of thymic factors and the development of NK as T-cell precursors.     

Effect of T-activin on the production of immune interferon

A study was made of the effect of T-activin on the biosynthesis of immune gamma-interferon. It was shown that in 27% of patients with chronic nonspecific pulmonary diseases, production of gamma-interferon by lymphocytes was substantially reduced during exacerbation of inflammatory process in the lungs. It was discovered that T-activin was not an interferon inductor but enhanced its synthesis in patients with a low capacity of producing immune interferon even at small doses of interferon inductor. The preparation does not produce any effect on this process in normal subjects and in patients showing the normal level of gamma-interferon. Thus T-activin can be used for stimulation of interferonogenesis.     

Effectiveness of correcting radiation injuries of the thymic endocrine function by T-activin in conditions of reduced postradiation hypercorticism reaction]

T-activin administered to rats after exposure to whole-body 1.5 Gy neutron- and 6 Gy X-radiation increases considerably the thymosin-like serum activity, accelerates cellularity restoration in the thymus and spleen, but does not influence the survival rate. Ionol administered prior to X-irradiation reduces the postirradiation hypercorticism reaction and the indirect effect of radiation on lymphoid organs which it is responsible for. The combined injection of ionol and T-activin increases the thymosin-like serum activity and spleen cellularity to the highest possible level and increases the survival rate of rats from 24 to 64 per cent and the lifespan up to 6 days.     

Effect of T-activin on the formation of conditioned reflex and manifestations of unconditioned reflex of avoidance in August strain rats]

It has been revealed that intraperitoneal injection of T-activin (humoral factor of the thymus) to August rats leads to more rapid and stable conditioned reflex formation to a sound and to a decrease of avoidance time when electric current is given to a shuttle chamber. Furthermore, less amount of uneffective series in testing unconditioned avoidance is registered in the test animals. A positive T-activin effect on conditioned reflex formation and unconditioned reflex manifestation is probably connected with its ability to alter hippocampus functional parameters and (or) with anti-stressor properties of the preparation.     

Thymus involution and recovery in mice after the administration of lipopolysaccharide

The single injection of 50 micrograms LPS induces polyclonal immune response in the spleen of (CBA x C57B1/6) F1 mice. It is accompanied by the thymic involution and depletion of blasts and mitoses, as showed morphometric analysis. Vinblastin does not induce: accumulation of the mitoses during the first and second days after LPS injection. The regeneration of the thymus begins already from the second day with increasing of blast cells, reaching a maximum at the 3rd day. The mitosis wave retards two days and achieves peak at the 5th day. The regeneration of the thymus finishes at the 13th day aster LPS injection, but the blast number is higher, than the control level.     

Thymic hormones in radiation-induced immunodeficiency. I. Induction of mature interleukin 1 responsive cell in the thymus by thymosin fraction 5

The restorative effect of thymosin fraction 5 (TF5) on the thymus of gamma-irradiated mice was examined. Four different mouse strains were used in this study since earlier work determined that the degree of response to TF5 is strain dependent. The responsiveness to comitogenic effect of interleukin 1 (IL-1) was used to measure the rate of recovery of immunocompetent cells in the thymus, since only more mature PNA-, Lyt-1+-2- medullary cells respond to this monokine. Contrary to several earlier reports that radioresistant cells repopulating the thymus within the first 10 days after irradiation are mature, corticosteroid resistant, immunocompetent cells, the thymic cells from irradiated mice in all strains used had greatly reduced responses to IL-1. Daily intraperitoneal injections of TF5 increased significantly the responses of thymic cells to IL-1 in 10- to 13-weeks-old C57Bl/KsJ, C57Bl/6, C3H/HeJ, and DBA/1 mice. Older mice, 5 months or more in age, of DBA/1 strain did not respond to treatment with TF5. However, C3H/HeJ mice of the same age were highly responsive. In conclusion, (1) cells repopulating the thymus within 12 days after irradiation contain lower than normal fraction of mature IL-1 responsive cells, (2) thymic hormones increase the rate of recovery of immunocompetent cells in the thymus, and (3) the effect of thymic hormones is strain and age dependent.     

Studies of the influences of pregnancy and lactation on the thymus in the mouse

Summary Influences of pregnancy and lactation on the thymus were quantitatively and microscopically studied in the mouse. Thytnic involution due to pregnancy occurs in later pregnancy and reaches a maximum at parturition. After parturition the involuted thymus regenerates, but lactation has an inhibitory influence on the regeneration. The possible significance of the thymic changes is discussed particularly in relation to the adrenocortical activity. Histologically the cortex exhibits prominent alterations during the involution and regeneration. The pattern of depletion and repopulation of lymphocytes in the cortex is similar to that in other types of acute involution. The medulla also undergoes microscopic changes which are revealed particularly by the histometric examination of its components.     

Indomethacin inhibits thymic involution in mice with streptozotocin-induced diabetes

Diabetes is chronic disease that is accompanied by a rapid thymus involution. To investigate the factors responsible for thymic involution in a model of STZ-induced diabetes, mice were injected with STZ alone or in combination with the cyclooxygenase 2 inhibitor indomethacin (INDO). Thymus weight, glycemia and serum corticosterone were measured, and apoptosis in thymus and thymocyte cultures was analyzed by flow cytometry. Although earlier studies report that streptozotocin (STZ) is toxic to lymphoid tissues, in our experiments even massive doses of STZ did not negatively affect thymocyte cultures. Cultured thymocytes also seemed unaffected by high glucose concentrations, even after 24 h of exposure. Administration of INDO concomitantly with STZ reduced thymic involution but did not prevent the onset of hyperglycemia or reduce established hyperglycemia. When INDO was given before STZ, the same degree of thymic involution occurred; however, hyperglycemia was reduced, although normoglycemia was not restored. INDO also reduced serum corticosterone. Because thymocytes are known to be sensitive to glucocorticoids, this finding suggests that cyclooxygenase 2 inhibition may retard thymic involution by reducing serum glucocorticoids. In conclusion, our results show that STZ and hyperglycemia are not toxic to thymocytes and that cyclooxygenase 2-mediated mechanisms are involved in thymic involution during diabetes.     

Morphometrical analysis of the thymus from mice submitted to low temperature

Thymic involution is a slow physiological process than can be accelerated by some pathological or experimental conditions. In this work we kept male mice under low temperatures in order to observe whether or not thymic involution would be promoted. For this purpose, we carried out a histometrical analysis of the thymus and observed that there was a decrease in both cortical and medullary regions of the thymic lobules. These changes paralleled a loss in the absolute and relative weights of the thymus. It was concluded that low temperatures induce thymic involution even in nonhibernating animals.     

Quantification of thymic innervation in juvenile and aged rats.

Thymic innervation has been quantified using silver impregnation and light microscopy on 5 juvenile and 5 aged rats. There is an increase in innervation density of the thymus with age, exceeding the reduction of thymic volume due to involution. The density of innervation correlates inversely with thymic volume. From previous studies, we conclude that thymic innervation is confined to the extraparenchymal compartment. Ultrastructural morphometry shows this compartment to maintain its volume during involution of the remaining thymic tissue. Related only to the extraparenchymal compartment, the innervation increases by a factor two with age.     

The effect of using T-activin in the therapy of the newborn with suppurative surgical infection

A total of 156 newborn infants with suppurative surgical infection (SSI) were observed; 73 of them had sepsis and 83 a severe localized process. In 47 patients with sepsis and 34 with localized infection, T-activin was included in complex therapy while the other infants formed the control group. It has been established that T-activin leads to an increase in the quantity of the active population of T-lymphocytes in the peripheral blood and to enhanced functional activity of T-lymphocytes in the newborn with SSI independent of generalization of the process. Bactericidal activity of circulating phagocytes is improved. The clinical course of SSI is less severe with more pronounced positive changes in the symptoms, hospital stay of the children is shortened, lethality is reduced. The effect of T-activin on the dynamic of the indices of the immune state is more marked in a septic process.     

Measurement of thymus weight, lumbar node weight and progesterone levels in syngeneically pregnant, allogeneically pregnant, and pseudopregnant mice.

Female CBA mice were mated to fertile CBA males, to vasectomized CBA males, to fertile C57BL males or to vasectomized C57BL males. After allogeneic or syngeneic mating the extent of thymic involution on the 10th day of pregnancy and pseudopregnancy was similar. Lumbar lymph node weight was not affected by pseudopregnancy but increased similarly in allogeneic and syngeneic pregnancies. Serum progesterone levels on the 10th day of pseudopregnancy were similar to those of non-pregnant females, and significantly lower than those of pregnant females. On the 4th to 7th days progesterone levels in pseudopregnant animals were equal to those in pregnant animals. Progesterone levels and thymic involution were similar in syngeneically and allogeneically pregnant females. Progesterone levels were negatively correlated with thymus weight but reached significance only when the mating was allogeneic. It is suggested that there is an interaction between progesterone concentrations and the degree of thymic involution during pregnancy.     

Interaction of T-activin with peritoneal macrophages

The action of T-activin on peritoneal macrophages of CBA mice after its introduction into the animals has been studied. In intact mice the phagocytic activity of macrophages and their resistance to the cytopathogenic action of Salmonella typhimurium live cells remains unchanged. The injection of corpuscular pertussis vaccine into mice leads to a decrease in the resistance of macrophages to the action of salmonellae. The simultaneous injection of T-activin into mice in doses of 0.1 and 1.0 microgram per animal abolishes the damaging action of the vaccine. The analysis of the in vitro action of T-activin on macrophages of intact mice revealed that the preliminary incubation of cells with the preparation sharply increases their resistance to the action of salmonellae, while its introduction simultaneously with bacteria or after them rapidly leads to the death of macrophages. The action of T-activin is supposed to be linked with triggering the biosynthetic processes mediating the resistance of macrophages to the cytopathogenic action of salmonellae.