Physicochemical properties of the human lymphocyte mitogenic factor induced by phytohemagglutinin]

Some physical and chemical properties of the mitogenic factor (MF) produced in vitro by PHA-stimulated human lymphocytes were investigated. Treatment of the culture medium with proteases proved to decrease the MF activity sharply. The MF was found to have an elution pattern in Sephadex and Bio-gel gels similar to proteins with the molecular weight of 20 000--30 000 daltons (peak--25 000). In experiments with the MF fractionation by disc-electrophoresis on 5% polyacylamide gel the MF formed a few discrete peaks in the fractions corresponding to the mobility of alpha1- and alpha2-globulins and transferrin. In isoelectric focusing the MF formed 3 fractions in the pH range of 4.5--8.3. Functional heterogeneity of the MF is suggested.     

Effect of highly purified thymus factor on the cellular and humoral indices of immunity in thymectomized mice]

Effect of homogeneous polypeptide thymus factor of mol weight about 5000 (thymarin-III) on cellular and humoral immune responses of thymectomized adult CBA mice was studied. Thymectomy proved to greatly decrease the number of T-cells in the spleen. Accordingly, the capability of these mice to produce both IgM and IgG antibody-forming cells in response to the thymus-dependent antigen (sheep red blood cells) was significantly depressed. Subcutaneous injections of thymarin-III (1 microgram per g of body weight) for 7 days completely restored the T-cell spleen population and normalized the animals' immune response.     

Modification of radiation sensitivity of lymphocytes of the rat thymus gland using cholesterol-enriched autoliposomes]

The influence of thymocyte enrichment with cholesterol on radiosensitivity of these cells has been studied. The enrichment was performed using autoliposomes. It was found that in the modified cells the processes of lipid peroxidation, enzymatic degradation of chromatin and apoptosis are inhibited.     

Study of the thymus as a source of humoral factors stimulating antibody formation]

A fraction stimulating antibody formation in neonatal animals was obtained in separation of the calf thymus extract (1A) prepared by the method of Goldstein et al. on a column with Sephadex G-25 (fine). Testing of the activity of analogous fractions of the extracts of calf tonsils, spleen, lymph nodes and the liver led to a supposition that the thymus was the only source of specific humoral factor stimulating antibody formation, which could accumulate in the peripheral lymphoid formations. Low activity of tonsillar extracts failed to confirm the hypothesis on the role played by the tonsils as the central immunity organ similar to the bursa Fabricii.     

Effect of the low molecular weight thymus factor on T-cells in human blood]

Lowmolecular factor of polypeptide nature (thymarin) was extracted from calf thymus. This factor differed by physical and chemical characteristics from thymosin. The percentage content of "active" T-lymphocytes increased under the effect of thymarin in the cultures of lymphoid cells obtained from healthy individuals. The total T-cell count remained unchanged. Thymarin favoured increase of the total T-lymphocyte and "active" T-lymphocyte count in the cultures of cells from patients with chronic inflammatory processes. Cellular immunity reactions were restored and the course of the main disease improved under the effect of parenteral administration of thymarin. It is supposed that T-immunity system incompetence was associated with the inadequate production of the thymus factor capable of restoring the activity of the thymus-dependent lymphocyte population.     

Effect of the lining of the thymus gland on hematopoietic stem cell kinetics in a suspension of embryonic mouse liver]

A study was made of the kinetics of hemopoietic stem cells in the organic culture of a suspension of mouse embryonic liver cultivated directly on the filters and on the preliminarily grown embryonic thymic feeder. It was shown that stem hemopoietic cells were retained in the course of one month of cultivation in the embryonic liver suspensions; during the first two weeks hemopoiesis in the suspension practically failed to differ from such in the fragments of the same age and cultivation period, whereas during the subsequent periods hemopoiesis proved to be more active in the suspension cultivated on thymic feeder. A possible participation of the thymus in the hemopoiesis is discussed.     

Cytological structure of the thymus gland in mature monkeys]

Histological sections of the thymus were studied morphometrically in 5 rhesus monkeys and 3 hamadryas baboons. The ratio of square surfaces of the cortical and cerebral substance, the percentage of Hassall's corpuscles and cellular elements (lymphocytes, stromal elements, blasts etc.) were established in the organ. Individual and species peculiarities of the structure of thymus elements were found. Less amount of parenchyma and growth of the stroma in baboons and a greater mitotic complex in rhesus monkeys show more pronounced involution processes in baboons.     

Effect of a modifying factor on the sensitivity of Crithidia oncopelti to levorin

The paper deals with possible discovery of ways for increasing sensitivity of trypanosomides to polyenic antibiotics. The following substances were tested: sodium pyruvate and acetate, calcium salts, ascorbic acid and 1-valine. The total number of the cells and the number of the viable cells in the culture and their morphological characteristics were used as the criteria for estimation of the C. oncopelti sensitivity. It was shown that sodium acetate most actively modified the levorin effect on C. oncopelti. Its addition in a concentration of 40 mg/ml to the cultivation medium with levorin in a concentration of 1 microgram/ml induced a trypanocidal effect. With the use of levorin alone such an effect was observed when the antibiotic was used in a concentration of 10 micrograms/ml. The growth rate of the protozoon was decreased by 60-80 per cent as compared to the control. The number of the viable cells was lowered 4 times. The morphology of the culture markedly changed. This indicates that the presence of sodium acetate as a modifier in the culture medium allowed one to decrease 10 times the dose of levorin and to preserve the trypanocidal effect.     

Bovine milk lactoferrin modulates the proliferative lymphocyte response to phytohemagglutinin

Bovine milk lactoferrin (2 to 20 g ml^–1) changed enhancement of [³H]thymidine incorporation by phytohemagglutinin-stimulated rat spleen lymphocytes into suppression as their lactoferrin-withdrawal incorporation increased to greater than 10000 cpm culture^–1 under the present isotope-labeling conditions. The enhancement disappeared by 15-min delayed addition of lactoferrin after addition of lectin. There was no lactoferrin effect when the cells were stimulated with 12-O-tetradecanoylphorbol-13-acetate plus ionomycin. Thus, lactoferrin has a certain extracellular effect on lymphocyte proliferation in response to the lectin.     

Influence of genital hormones on guinea pig thymus gland cytology]

The changes of the thymic cytologia under the action of genital hormones were studied in giunea pigs. The conclusion of the experiments was: the oestrogens are the only hormones to induce a fast and complete involution of the thymic tissue with appearance of Foa-Kurloff cells'. The cell seems to have all the necessary characters to be the morphologic substratum of an eventual cytocrine secretion of the thymus.