[Detection of DNA sequences sensitive to glucocorticoids in the thymus of AKR mice and their inactivation in thymoma]. / Obnaruzhenie chuvstvitel'nykh i gliukortikoidam posledovatel'nostei DNK v timuse myshei linii AKR i ikh inaktivatsiia v timome.

A high increase in transcriptionally active DNA fraction (TA DNA) has been detected in the thymus of young AKR mice and in thymoma. Hybridization of TA DNA with [32P] cDNA synthesized on poly A+-mRNA of cortisol-induced animals has shown that TA DNA of young AKR mice contains 40 times as much cortisol-activated repeated sequences (RS) as that of thymoma. The decrease of cortisol-activated (RS) in AKR thymoma TA DNA was found to be the result of their transition into transcriptionally inactive (TI) DNA. It is concluded that chromatin conformation changes take place in cortisol-activated RS DNA region of AKR mouse thymus before transformation. Unstable conformation of RS DNA in the thymoma can possibly promote their transition into TI DNA.

[Mechanisms of insulin action on antibody-forming cells in vitro]. / K voprosu o mekhanizmakh deistviia insulina na antiteloobrazuiushchie kletki v usloviiakh in vitro.

The influence of different doses of insulin on the quality of plaque forming cells (PFC) has been studied in the spleen cell suspension of immune mouse in vitro, the effect of insulin being dose depending. The quantity of PFC in vitro increased during the incubation with a large dose of insulin and decreased with a small dose. The influence of specific activators and inhibitors of cyclic nucleotides on the effect of insulin has been revealed. It is suggested that insulin may exert its influence on the appearance of PFC through changing the relationships of intracellular cyclic nucleotides.

[Effect of the cAMP-dependent phosphorylation of sheep erythrocyte membrane on their ability to induce a humoral immune response]. / Vliianie tsAMF-zavisimogo fosforilirovaniia membran éritrotsitov barana na ikh sposobnost' k induktsii gumoral'nogo immunnogo otveta.

It was found that the immunization of mice with sheep red blood cells (SRBC) phosphorylated under conditions of cAMP synthesis induction led to a more than 3-fold decrease in the number of antibody-forming cells (AFC) in the mouse spleen as compared to control. Phosphorylation of SRBC led to a 2-fold and 3-fold reduction in the activity of cAMP-independent and cAMP-dependent protein kinases. It is assumed that the decreased immune response to phosphorylated SRBC is consequent on the inactivation of a certain percentage of SRBC antigenous determinants and that an important part in the recovery of their activity is played by the action of cAMP-dependent protein kinase membranes.

[Effect of combined administration of hydrocortisone and EDTA on the number of the antibody-producing cells in the spleen of mice immunized with sheep erythrocytes]. / Vliianie sovmestnogo vvedeniia gidrokortizona i EDTA ns kolichestvo antiteloobrazuiushchikh kletok v selezenke myshei, immunizirovannykh eritrotsitami barana.

Experiments on mouse hybrids (CBA X C57BL)F1I indicated that injection of hydrocortisone in a dose of 1 mg/mouse 24 hours after the immunization with sheep red blood cells against the background of multiple EDTA injection resulted in a relative reduction of the plaque-forming cells in the spleen--more than 6-fold in comparison with control, and more than 3-fold in comparison with the effect of hydrocortisone or EDTA alone. This may possibly be the consequence of a more intensive hydrocortisone incorporation under conditions of prolonged hypocalciemic action of EDTA complexon.

[Ca++-dependent immunosuppressive effect of ethylenediaminetetraacetic acid (EDTA)]. / Ca++-zavisimyi immunodepressivnyi (effekt) etilendiamintetrauksusnoi kisloty (EDTA).

Subcutaneous injection of a sum total dose of 6.44.10(-5) M of ethylenediaminetetraacetic acid (EDTA), which binds divalent cations, inhibits the process of accumulation of antibody-forming cells in the spleen of mice (CBA X C57BL) F1 hybrids, immunizated with sheep red blood cells. In a dose of 5.2.10(-5) M CaCl2 eliminated the immunodepressive effect of EDTA almost completely. It was assumed that EDTA action was produced through the Ca++-controlled regulation mechanism of one of the following processes: the interaction between T- and B-lymphocytes; proliferation and differentiation of T- and B-cells in the course of the immune response to sheep red blood cells. A more complex mechanism of EDTA action on the above-mentioned processes is not excluded, however.