[Comparative characteristics of some parameters of the cell nucleus in the series myeloma-hybridoma-lymphocyte]. / Sravnitel'naia kharakteristika nekotorykh parametrov kletochnogo iadra v riadu mieloma-gibridoma-limfotsit.

A comparative study of several parameters of the cell nuclei of hybridoma MLC-1c and its parent cells--myeloma X-63.Ag8.653 and spleen lymphocytes of Balb/c mice, has been carried out. The results of cytogenetic studies suggest that although the hybridoma and myeloma cell lines used in this study are rather stable, they contain some proportion of the altered chromosomal material. Two-dimensional electrophoresis performed according to O'Farrell revealed that the similarity between the relative presentation and reciprocal location of the nuclear proteins expressed by the myeloma and the hybridoma was greater than that between these cell lines and lymphocytes. Probing of the chromatin structure by micrococcal nuclease showed no significant differences in the degree of nuclease resistance of chromatin between myeloma, hybridoma and lymphoid cells. A comparative study of the Ca/Mg-dependent endonuclease activity of the nuclei in situ and in nuclear extracts demonstrated that whereas its content in lymphocytes was rather high, in myeloma and hybridoma it was practically absent. At the same time, cell nucleus extracts of the myeloma and the hybridoma contained high amounts of DNA-binding proteins which were undetectable in mouse spleen lymphocytes.

[Identification of myosin light chain 1 from human heart ventricles on two-dimensional electrophoretograms using monoclonal antibodies]. / Identifikatsiia legkoi tsepi 1 miozina iz zheludochkov serdtsa cheloveka na dvumernykh élektroforegrammakh s pomoshch'iu monoklonal'nykh antitel.

Two-dimensional electrophoresis performed according to O'Farrell was used to isolate the myosin light chain I from human heart ventricles. This chain was further used to obtain hybridomas able to secrete monoclonal antibodies. This method permits to increase the yield of monoclonal antibody-secreting hydridomas and to spare effort with regard to cultivation and testing of experimental samples.

[Use of monoclonal antibodies in comparative studies of Ca, Mg-dependent endonuclease in cell nuclei]. / Primenenie monoklonal'nykh antitel v sravnitel'nykh issledovaniiakh Ca, Mg-zavisimoi éndonukleazy kletochnykh iader.

Eight hybridoma cell lines derived from fusion between myeloma X-63 and mouse splenocytes were found to secrete monoclonal antibodies against Ca/Mg-dependent endonuclease of human spleen cell nuclei. Two of them, termed N and S, were used in comparative research of enzymes from different organs and species of animals. The data obtained show that N and S antibodies recognize different antigenic determinants of the enzyme molecule. Cross-reactions of antibodies with different antigens having similar antigenic determinants, exist in Ca/Mg-endonuclease of such species as man, mouse, rat and cattle. The evolutionary conservatism of this enzyme is suggested. The data show that the existence of tissue-specific (thymus-specific and spleen-specific) isoforms of Ca/Mg-endonuclease of cell nuclei is possible.

[Production of antibodies by hybridomas in a serum-free culture medium]. / Produktsiia antitel gibridomami v pitatel'noi srede, lishennoi syvorotki.

Evidence is presented that hybridomas maintained in serum-free medium continue to secrete antibodies for some time. The dynamics of this secretion appears to be close to that in analogous cultures kept in the serum medium but apparently differs from that in analogous cultures grown in the balanced salt solution. The possibility of hybridomas to synthesize antibodies in protein free medium and not only to release those formerly synthesized is under discussion.

[Changes in the detectability of HLA antigens on lymphocyte subpopulations induced by mitogens and corticosteroids]. / Izmenenie vyiavliaemosti HLA antigenov na subpopuliatsiiakh limfotsitov pod vliianiem mitogenov i kortikosteroidov.

A study was made of changes in the detectability of HLA-A, HLA-B and HLA-DR histocompatibility antigens on subpopulations of immunocompetent cells under the effect of mitogens and corticosteroids. HLA-antigens were identified by the lymphocytotoxic test. It was found that cell cultivation and mitogen stimulation lead to the fact that distinct reaction with the cells is produced by a greater number of HLA-antisera, while the specificity of direct and cross reactions remains unchanged. The main contribution to changes in the detectability of HLA-antigens is made by T cells. The exposure of the cells to dexamethasone in a dose producing no cytotoxic effect drastically lowered cell proliferation under the effect of PHA and deteriorated the detectability of HLA-A and HLA-B antigens. As regards HLA-DR antigens, it was disclosed that PM-stimulation of B cells considerably decreased the expression of their antigens, whereas PHA-stimulation of T cells led to the detection of HLA-DR antigens on these cells.

[Changes in the expression of HLA-antigens on lymphocytes after certain types of treatment]. / Izmenenie ékspressii HLA-antigenov na limfotsitakh pod vliianiem nekotorykh vozdcístvii.

The microlymphocytotoxic test was used for typing HLA-A and HLA-B antigens of peripheral blood lymphocytes in normal subjects. Cultivation of lymphocytes for 72 hours signifies that distinct reaction with the cells is produced by a greater number of HLA-antisera, with the specificity of direct and cross reactions being unchanged. Addition of mitogens to the cultural medium further increases the number of reacting antisera. The treatment of lymphocytes with cyclophosphan (an activated form) in doses not leading to the dealth of the cells but inhibiting cells proliferation completely eliminates the above effect. Stimulation of such cultures with mitogens did not entail the increased number of positive reactions. Possible mechanisms of the phenomenon under consideration are discussed.

[Supressor activity of spleen cells during medically induced immunologic tolerance]. / O supressornoi aktivnosti kletok selezenki pri lekarstvenno indutsirovannoi immunologicheskoi tolerantnosti.

SRBC tolerance was induced in mice (CBA X C57BL/6) F1 by single intraperitoneal injection of 6 X 10(9) SRBC and of cyclophosphamide (100-200 mg/kg) in 44-46 hours. Spleen cells of tolerant mice obtained at various periods after the tolerance induction (in 12-26 days) failed to decrease their immune response to SRBC after administration to intact syngeneic recipients. Contrary to intact mice, tolerant animals were incapable of producing suppressor cells after a single SRBC immunization. Only when 3 additional injections of high SRBC doses (6 X 10(9)) were given to tolerant mice the spleen cells in them acquired the capacity to inhibit the immune response after administration to normal mice. It is supposed that the absence of suppressor cells in induction of the immunological tolerance by means of cyclophosphane was caused by the processes of clone elimination. Suppressor cells can originate in tolerant animals under the effect of intensive antigenic stimulation, this leading to enhancement of the tolerance state as a result of additional SRBC injections.