R. V. Petrov

Bivalphor: a myelopeptide possessing antitumor activity

It is shown that the bone marrow-derived hexapeptide bivalphor restores the functions of human T lymphocytes inhibited by products of HL-60 leukemia cells.

A stimulator for antibody producers isolated from supernatants of human bone marrow cell cultures in health and disease

The study of mediators determining functioning of the immune system is currently receiving much attention. Some of these mediators, such as interleukins [8, 9], 7-interferon [15], macrophage migration inhibition factor [13], growth factors of T and B cells [ii, 14], etc., are produced by immunocompetent cells after introduction of an antigen into the body whereas others are synthesized by cells of central lymphoid organs (thymus and bone marrow) continuously, irrespective of antigenic stimulation. These include, primarily, hormones synthesized by the reticuloendothelial stroma of the thymus. Cells of the other central organ of immunity, namely bone narrow, also synthesize various mediators which influence immune reactions.

Comparison of complement-fixing activity of model immune complexes of different molecular weight

: The authors studied and compared the complement-fixing activity of model immune complexes with different molecular mass. The complement-fixing activity of the complexes was found to be linearly independent of the molecular mass, being mainly determined by the size of the complex, and to be slightly dependent on the concentration of aggregated immunoglobulins. As far as the aggregates with a molecular mass over 20 IgG are concerned, addition of complement leads to the dissociation of the complexes.

Effect of molecular weight of aggregated immunoglobulins on their complement-fixing ability

complexes are deposited in the thymus. The location of the complexes in different zones of the thymic lobule is evidence that different subpopulations of thymic lymphocytes undergo changes in these diseases. In conclusion it must be pointed out that, although the causes of the changes in thymic tissues in myopathy are not yet known, the very fact that such changes are present suggests that immunopathological disturbances due to injury to the central organ of the lymphoid system play an important role in the development and course of this disease.

Investigation of IgE by thermistography

Since the IgE concentration in the blood serum is low and since its isolation and purification are very difficult, its structure, functions, and physicochemical properties have not been adequately studied. The most widely used methods of IgE determination are currently radioimmunologic [8, 10], but despite certain advantages, these are very laborious and expensive. The use of new methods and techniques for the investigation of IgE is therefore an extremely promising development. The method of thermistography [4] has been used to determine the serum immunoglobulin levels. By the use of this method it is possible to detect a low IgA level (of the order of nanogram/millileter) in patients with ataxia-telangiectasia, whereas by the usual Mancini immunodiffusion method, IgA was not found in these patients.

Specific complex formation by human immunoglobulins and their corresponding antibodies

Specific complex formation by human immunoglobulins of classes M, G, and A with antibodies against class G immunoglobulins was studied by a thermistographic method. Depending on the type of interacting immunoglobulins, the rate and intensity of the process were shown to differ and to be maximal for IgM. Depending on the character of the curves obtained the class of immunoglobulins being synthesized at that given moment could be determined. Disturbance of the internal structure of the macromolecules of the immunoglobulins, as a result of heating, for example, leads to changes in the mechanism of complex formation; the important question in this event is which of the interacting components undergoes denaturation.

Study of the molecular mechanisms of formation of complement-immunoglobulin complexes

Complement is known to be a multicomponent system [5, 7, i0], consisting of nine serum proteins, and it plays an important role in in~unogenesis. The components of complement are biologically inert, but under certain conditions they are activated by the ant• (Ag-~b) complex or by aggregated immunoglobulins of antiserum, when they acquire the functions of enzymes and perform a protective or destructive role in immunocytolysis.

Action of di-iodobenzotepa on functionally different T-lymphocyte subpopulations

Di-iodobenzotepa (DIB) was given per os daily for 3 days in a dose of 25 mg/kg to CBA mice. A decrease in the number of nucleated cells in the thymus by 74% and in the bone marrow by 29% was observed. Experiments with transplantation of lymphocytes from mice treated with DIB into intact or lethally irradiated (CBAxC57BL/6J)F1 mice showed that DIB has no effect on the helper activity of T-lymphocytes but depresses the functional activity of B-lymphocytes and t-lymphocytes, inducing the graft versus host reaction, and of T-suppressor cells.

Migration of hematopoietic stem cells after burns

Experiments on (CBA×C57BL)F1 mice showed that during the period of a sharp rise in the blood endogenous glucocorticoid level 30 min-6 h after burns the number of circulating colony-forming units (CFU) falls by 50–60%. At the same time migration of CFU from an area of bone marrow screened during irradiation (850 R) was inhibited. On the 3rd-4th day after burns, migration of CFU was intensified.Experiments on (CBA×C57BL)F1 mice showed that during the period of a sharp rise in the blood endogenous glucocorticoid level 30 min-6 h after burns the number of circulating colony-forming units (CFU) falls by 50–60%. At the same time migration of CFU from an area of bone marrow screened during irradiation (850 R) was inhibited. On the 3rd-4th day after burns, migration of CFU was intensified.

Nature of a humoral factor of bone marrow stimulating antibody production

A fraction doubling the quantity of antibodies synthesized in a culture of cells from immune lymph nodes was isolated by gel chromatography from the supernatant obtained after culture of bone marrow cells from intact donors. The stimulator of antibody producers (SAP) was eluted in the region of emergence of cytochrome C with a molecular weight of 13,000 daltons and it was thermostable. Synthesis of RNA and protein was essential for its production, but DNA synthesis was not necessary. Incorporation of radioactive label showed that the SAP contained ribonucleotides and amino acids. It is suggested that this factor plays an important role in the regulation of antibody synthesis.