In the previous in vivo experiments it was shown that macrophages could modify the direction of haematopoietic stem cell (CFU-S) differentiation from erythroid to myeloid one, when injected simultaneously to lethally irradiated mice. Stable absorption of 50% CFU-S on the macrophage monolayer was documented in in vitro experiments, when it was incubated for 1 hour together with bone marrow cells. After administration to syngeneic recipients the CFU-S adsorbed by macrophages formed myeloid spleen colonies mainly. The nonadsorbed part of CFU-S underwent similar changes in the direction of differentiation, but only after a longer (2.5 hour) coincubation. The involvement of monokines in the control of the early differentiation of haematopoietic stem cells is suggested.

The liver lesion in the CBA mice has been induced by administration of one of three agents five times every day; gamma-globulin fraction of antihepatocytotoxic serum in doses of 4.8 and 7.7 mg of protein per 100 g of body mass; gamma-globulin fraction of normal rabbit serum and bovine serum albumin in a dose of 4.8 mg of protein; three- four- or five-fold introduction of carbon tetrachloride in a dose of 0.5 ml per 100 g of body mass with oil (1:1) each three days; calibrated stenosis of the portal vein was produced. The total number of hemopoietic stem cells in the bone marrow was estimated by the colony-forming unit/spleen assay. Histological analysis of the colony-forming units was applied. The liver lesion was accompanied by a decrease in the ratio of the erythroid/granulocytic colonies.

Topography of catecholamine-containing (CA) neurons of the cat locus coeruleus was studied using a combination of the catecholamine histofluorescence method and rapid embedding of the brain tissue into the paraffin wax. The distribution of CA neurons was examined at frontal and sagittal sections of the brain stem. Unlike that shown previously the quantity of CA neurons in the rostral pole of the locus coeruleus was somewhat higher while at the frontal level of P--2.0-P--4.0 the significant number of CA cells of the locus coeruleus was localized more ventromedially.

Haemopoietic stem cells of mice which displayed an increased radioresistance 12 days following sublethal irradiation, exhibited higher proliferative, granulocyte-repopulating and migration activities as compared with those of intact animals.

Distribution of CFU-S upon daily chronic irradiation of mice with doses of 0.25 and 0.5 Gy during 3-4 months was close to normal: the percentage of individuals without CFU-S capable of forming macrocolonies being high in both cases. 60 day after the end of the exposure the macrocolony-forming ability after the second transplantation was nearly twice as low and independent of daily dose and duration of exposure.

In experiments with mice, rats, guinea pigs, and dogs subjected to whole-body irradiation a favourable effect of postirradiation explantation, incubation, under suboptimal conditions, and reimplantation of bone marrow cells was shown. The effect was perhaps associated with the enhanced recovery of stem cells, their primary differentiation into a granulocytic series, and activation of bone marrow regeneration.

A new monoclonal antibody that recognizes a new antigen on the surface of mouse teratocarcinoma F9 stem cells has been described. This antigen is a glycolipid as demonstrated by inhibition of immunofluorescence by different monosaccharides, glycoproteins and glycolipid fraction of F9 cells as well as by chemical analysis. Immunofluorescent staining of in vitro cultivated preimplantation mouse embryos has demonstrated that this antigen is specific only of internal cell mass cells of late blastocyst.

Changes in primordial lymphoid organs (bone marrow and thymus) with respect to the content of a serum thymic factor in the blood and specific activity of end desoxynucleotidyltransferase in the bone marrow and peripheral blood were studied in patients with chronic glomerulonephritis with and without the nephrotic syndrome. The mechanisms of autoimmunization were also studied with respect to the presence of renal tissue autoantigen antibodies. Alteration of primordial lymphoid organs was not attended by the autoimmune changes, i.e. production of the renal autoantigen antibodies was not increased. This makes difficult interpretation of the nephrotic syndrome as an autoimmune process and of glomerulonephritis as a whole. Lymphocytes bearing end desoxynucleotidyltransferase more probably participate in the developmental mechanisms of chronic glomerulonephritis.

The expression of antigens on granulocyte-macrophagal colony-forming cells of patients with nonhematological diseases was studied. Treatment of bone marrow cells with murine monoclonal antibodies ICO-1 and ICO-11 led to statistically significant inhibition of the number of growing colonies. Monoclonal antibodies ICO-02, ICO-10, ICO-GM-1 and ICO-G-2 had no such effect.

The authors studied the radiosensitivity of CFU-s, forming 7- and 11-day colonies from fetal liver (FL) of 14 and 17 day gestation and bone marrow (BM) of adult mice. The index of D0 for 7-day colonies, formed by CFU-s from 14-day, 17-day FL and BM was 2.02; 1.57 and 0.78 Gy, accordingly. 11-day CFU-s both from FL, and from BM did not distinguish statistically at their radiosensitivity (their D0 was 1.25 Gy).

The authors studied the ability of the CFU-s, forming colonies on the 8 and 11 day after transplantation of cells from fetal liver (FL) of 14-18 day gestation and adult mouse bone marrow (BM), to repair the sublethal radiation damages (SRD), according to Elkind's model. The ability to repair the SRD of 11-day CFU-s (both EL- and BM-derived) was lower than the ability of 8-day CFU-s. Both subpopulations of CFU-s (as 8-, as 11-day) from FL have a reduced index of SRD reparation as compared with the corresponding meanings for BM.

The studies were performed on Wistar rats with acute myeloblastic leukemia induced by a prolonged administration of tritiated water (370 MBq/kg/day-1; an absorbed dose--25.3 Gy) and by repeated pyrogenal injections. A reduction of the pool of polypotent hemopoietic cells (CFUs) with a simultaneous increase of their proliferative activity and a decline of their ability to self-supporting were observed in the leukemia-bearing animals. Populations of CFUdc in DC and of CFUc were reduced in all cases; their colony-forming ability was also found to decrease. All animals with leukemia showed a lowered amount of CFU-BL in the bone marrow and of CFU-TL in the thymus, although the content of these cells in the peripheral blood remained unchanged.

A new model of chronic myelogenous leukemia (CML) pathogenesis based on the idea of some cellular clones dominance over the others at the stem cells level is described. The model gives good explanations to all basic clinical variants of CML as well as to all well-known cytological phenomena to be found recently in this type of leukemia. The most probable mechanisms which might be responsible for the above-mentioned phenomenon of dominance between different cellular clones are discussed.

Mathematical models of lymphopoietic variations in mammals exposed to acute and chronic irradiation have been developed. They are based on the cheilone theory of hemopoiesis regulation. The models are systems of 9 nonlinear differential equations. They give a qualitative and quantitative description of lymphocytes in peripheral blood and their precursors in bone marrow of irradiated mammals. These models have for the first time simulated the stimulating effect of prolonged irradiation with small dose rates on recovery processes in the lymphopoietic system.

Mathematical models of the time course of formation of platelets, erythrocytes, granulocytes and lymph cells of mammals have been developed. They are systems of nonlinear differential equations where concentrations of mature blood cells and their bone marrow precursors are the variables. The models represent the main stages in the development of the various types of blood cells and allow for specific formation of red and white blood cells. Verification with the aid of oscilation theory methods and computer-aided numerical calculations have shown that the models reproduce all dynamic variations of the hemopoietic system, including stable fluctuations of concentrations of the various types of blood cells and their precursors (limiting cycles). Calculated parameters of stable fluctuations are in good agreement with experimental data. Within the framework of the models the origination of limiting cycles is described and their interpretation is given. These models can be used to simulate monthly biologic rhythms inherent in the various types of hemopoiesis as well as to analyze flight biomedical data and to discriminate space flight effects on hemopoiesis.

ICO-63, new monoclonal antibodies (MCAB), used for immunodiagnosis, were produced by the standard hybridoma technique ICO-63 MCAB reacted with 50% granulocytes, 20% thrombocytes and endothelial cells, whereas they did not react with peripheral blood mononuclear cells, thymocytes and erythrocytes. The molecular weight of ICO-63 MCAB-identified antigen was about 100 kD. ICO-63 MCAB reacted with 12 out of 15 neuroblastomas, with some solid tissue sarcomas and melanomas, but did not react with tumours of the epithelial origin.