[Characteristics of the reaction of immunologically tolerant mice to the polyclonal stimulant salmozan]. / Osobennosti reaktsii immunologicheski tolerantnykh myshei na poliklonal'nyi stimuliator sal'mozan.

The nonspecific stimulant of the immune response salmozan (Sal) increases the number of PFC against SRBC in intact mice, B mice (thymectomized, irradiated and reconstituted with embryonic liver cells), and in mice pretreated with cyclophosphamide (CY). This effect was decreased in mice pretreated with SRBC and CY. The subsequent injections of SRBC and Sal into tolerant mice did not increase the response under study. It is concluded that the effect observed is due to partial alteration of antigen-specific B cells of tolerant mice and this alteration cannot be explained by the lack of the regeneration of membrane immunoglobulins.

[A reactivity to polyclonal stimulation of immunogenesis with salmozan after its repeated administration]. / Areaktivnost'k poliklonal'noi stimuliatsii immunogeneza sal'mozanom posle ego povtornogo vvedeniia.

The injection of 100 micrograms of salmozan (polysaccharide isolated from Salmonella typhi somatic O-antigen) or 50 micrograms of Escherichia coli lipopolysaccharide into mice induced a considerable increase in the number of antibody-forming cells in the spleen in response to the injection of sheep red blood cells (SRBC) 2-3 days later. This polyclonal effect was essentially weaker if the animals previously received 500 micrograms of salmozan (9-10 days prior to the injection of SRBC). The absence of reactivity was not linked with antibodies to salmozan or with some other serum factor. The lymphocytes of nonreactive mice proved to be capable of polyclonal response in the adoptive system, and at the same time the polyclonal response of intact lymphocytes to salmozan in the body of nonreactive irradiated mice was essentially weakened. The features making the above phenomenon similar to, as well as different from, the so-called "endotoxin tolerance" are analyzed.

[Thymus-dependence of genetic resistance to (CBA x M523)F1 lymphocytes]. / Timuszavisimost' geneticheskoi rezistentnosti k limfotsitam (CBA x M523)F1.

The nature of cells responsible for the genetic resistance of lethally irradiated CBA mice to lymphocytes of (CBA x M523)F1 hybrids was studied. Preirradiation of the hosts was shown to abolish the resistance. The latter was generally recovered by syngeneic thymocytes or splenocytes while embryonic liver and bone marrow cells or splenocytes treated with anti-Thy-I serum plus complement before injection into host were ineffective. It is postulated that some cells with T cell characteristics are responsible for the phenomenon of parental resistance. These cells differ in several respects from T cells that mediate the transplantation immunity and from M cells that control other forms of the genetic resistance.

[Effect of thymectomy on induction of immunologic tolerance in the effectors of delayed hypersensitivity]. / Vliianie timéktomii na formirovanie immunologicheskoi tolerantnosti v éffektorakh giperchuvstvitel'nosti zamedlennogo tipa.

The influence of thymectomy (Tx) on induction of tolerance of delayed type hypersensitivity effectors (DHE) was examined. Tx did not interfere with induction of tolerance to sheep red blood cells (SRBC) achieved with combined injections of the massive dose of the antigen and cyclophosphamide (Cy). Tx resulted in prolongation of unresponsiveness. The injection of mice with the massive dose of SRBC alone also resulted in tolerance formation. However, this type of tolghtly depressed formation of DHE in intact but not in Cy treated mice. The results obtained are in agreement with the idea of the existence of diverse mechanisms of tolerance induction (clonic-deficient and suppressor). These data also suggest the existence of two subpopulations differing in susceptibility to Cy and Tx in DHE effectors and their precursors.

[Functional activity of T and B lymphocytes of mice undergoing spontaneous loss of tolerance]. / Funktsional'naia aktivnost' T-i B-limfotsitov myshei pri spontannoi utrate tolerantnosti.

The functional activity of splenocytes and thymocytes of mice tolerant to sheep red blood cells was investigated one and four weeks after tolerance induction. The tolerance was achieved by cyclophosphamide. The immunocompetence of thymocytes was fully reversed in lfour week time. The functional activity of T and B lymphocytes of the spleen was also partially recovered four weeks after tolerance induction. Preliminary thymectomy weakened but did not prevent completely the immunocompetence of T cells of the spleen from being recovered. No Tsuppressants were found in the thymus or spleen of the tolerant animals.

[Induction of immune tolerance to thymus-dependent antigen (sheep erythrocytes) in the absence of T-cells]. / Induktsiia immunologicheskoi tolerantnosti k timuszavisimomu antigenu (éritrotsity barana) v otsutstvie T-kletok.

The role of T cells in B cell tolerance induction to sheep red blood cells (SRBC) was studied in intact adult mice, in lethally irradiated mice injected with singeneic embryonic liver cells and thymocytes (TB-mice) and in animals functionally deprived of T cells--thymectomized, letally irradiated mice reconstituted with embryonic liver cells only (B-mice). Tolerance was obtained by treatment of mice with SRBC and cyclophosphamide (Cy). Cy-induced tolerance to SRBC was shown to be the result of the absence of specific T cells and partially of immunocompetent B cells. Suppression of immunoreactivity was observed not only in TB-mice but also in B-mice subjected to tolerogenic treatment. Splenocytes of tolerant TB-mice did not suppress the immune response of intact spleen cells to SRBC. The results obtained suggest the conclusion that B cells tolerance could be formed in absence of T cells.

[Effect of thymectomy on induction of immunologic tolerance in adult mice and on the recovery of initial immunoreactivity]. / Vliianie timéktomii na induktsiiu immunologicheskoi tolerantnosti u vzroslykh myshei i na vosstanovlenie iskhodnoi immunoreaktivnosti.

The tolerance to sheep red blood cells induced with cyclophosphamide became more profound and prolonged in mice thymectomized before or after the tolerance induction. The greatest immunocompetence depression was achieved when the operation was preformed 24 hours before the tolerogenic treatment. The results obtained confirmed the assumption that this form of tolerance was due to deficiency of a definite T-helpers clones.

[Relationship between T- and B-lymphocyte cooperation and their syngeneity]. / Zavisimost' kooperatsii T- i B-limfotsitov ot ikh singennosti

Cooperation efficiency of (CBA x C57BL/6) F1 thymocytes and CBA bone marrow cells in immune response to SRBC was compared with the syngenic combination of the same cells. Selectivity of interaction of the T- and B-lymphocytes of different origin was studied in incomplete cyclophosphamines (CBA x C57BL/6) leads to CBA chimerae, where donors were primed with SRBC and the recipients were either intact or tolerant to the given antigen. F1 T-cells proved to interact with the CAB-B-cells 10-15 times less effectively than with the syngenic B-cells. It is suggested that similarity between the antigenic structure of the cell membrane of the T- and B-lymphocytes, aiding their physical contact, increased the action efficiency of the T-mediator on the B-cell.

[Factors determining prolonged chimerism of lymphoid tissue in mice treated with cyclophosphamide]. / Faktory, opredeliaiushchie dlitel'nyi khimerizm limfoidnoi tkani u myshei, obrabotannykh tsiklofosfamidom

Conditions of long-lasting chimerism induction in adult CBA mice treated with cyclophosphamide and spleen cells (CBAXC57BL/6)F1 were investigated. The necessary requirements are high cell doses (over 50X10(6)), cyclophosphamide dose equal or over 200 mg/kg and a short interval (3-6hr) between their injections. The data obtained were interpreted from the point of view of the capacity of cyclophosphamide to induce reversible lymphocyte DNA damages. After the interaction of lymphocytes with the antigen these damages are fixed with the resultant elimination of the corresponding cell clone.

[Immunologic competence of T- and B-lymphocytes in tolerance induced by cyclophosphamide]. / Immunologicheskaia kompetentsiia T- i B-limfotsitov pri tolerantnosti, indutsirovannoi s pomoshch'iu tsiklofosfamida

A study was made of immunological competence of T- and B-lymphocytes of mice subjected to tolerogenic treatment (administration of a massive dose of sheep erythrocytes and cyclophosphamide 7 days before the experiment). The capacity of lymphocytes of tolerant mice to influence the interaction of normal T- and B-lymphocytes was also investigated. This form of tolerance was caused not by T-suppressors, but by a true deficiency of T-cells-helpers (both in the thymus and in the spleen), and partially of B-cells (in the spleen). Some lack of B-cells in the bone marrow was connected with a nonspecific action of cyclophosphamide. Cyclophosphamide is supposed to selectively eliminate cells proliferating in response to the antigen.