Mice were immunized with blood cells of a patient with chronic granulocytic leukemia, and their cells were subsequently used for the preparation of hybridoma ICO-02. This hybridoma is continuously producing monoclonal antibodies which reacted with cells in 4 out of 13 patients with blastic crisis of chronic granulocytic leukemia and in 6 out of 38 patients with acute lymphoblastic leukemia. Antibodies reacted with blast cells in 2 out of 3 patients with undifferentiated blastic crisis of chronic myelocytic leukemia and in 2 out of 5 patients with lymphoid variant of blastic crisis of chronic granulocytic leukemia. Cells of 6 patients with acute lymphoblastic leukemia which reacted with the monoclonal antibodies had immunological markers of T lymphocytes bone-marrow precursors. Monoclonal antibodies did not react with cells of blood and bone marrow from healthy people and from patients with chronic lymphocytic leukemia, acute myeloblastic leukemia, acute myelomonocytic leukemia, acute monoblastic leukemia and lymphosarcoma.

Quantitative regularities have been revealed in the regulatory action of B-lymphocytes from mouse lymph nodes on killer activity of T-lymphocytes of low electrophoretic motility. It was shown that the radiation-induced changes in the mode of action of B-lymphocytes may be attributed to a decrease in the number of active cells.

DNA content in the tumour cell nuclei was studied in 16 cases of early stomach carcinoma and in the adjacent areas of the foveolar epithelium dysplasia and metaplastic intestinal epithelium. One wave microspectrophotometry was used; the slides were stained with gallocyanin-chrome alum. The number of DNA synthesizing diploid cells was increasing with the increase of the dysplasia degree. The number of tetraploid cells was higher and the signs of aneuploidy appeared in the areas of noninvasive carcinoma. The stem line in early invasive carcinoma was represented by the diploid cells. The increase of cell atypia in tubular and papillary adenocarcinoma is followed by increase of the tetraploid cell number and by the appearance of polyploidy and aneuploidy. Both undifferentiated and goblet-cell carcinomas have similar parameters of the DNA histogram. DNA content allows an objective judgement on the degree of an early carcinoma cell atypia and differentiation of the advanced dysplasia and noninvasive carcinoma.

The experiments were carried out to study hemopoietic and stromal cells of bone marrow subendosteal regions during T-cell lymphomagenesis in AKR mice, using transmission electron microscopy and electron microscopic immunocytochemistry methods. It is shown that the subendosteal region of mice with lympholeukosis is replaced by lymphocytes at different stages of differentiation with certain ultrastructural peculiarities. The association of alkaline-phosphatase positive reticulum cells with granulocytes is destroyed. The alkaline phosphatase activity in reticulum cells of the subendosteal region of mice with spontaneous lympholeukosis is very low or absent. The results obtained may be useful for understanding the AKR lymphomagenesis.

Spleen colonies in the irradiated mice are produced by both stem cells and by their more differentiated progeny. In the latter case the colonies are transitory, ceasing 10-11 days after cell injection. The transitory colonies may be the cause of systematic artifact during the determination of stem cell proliferation. It was shown in particular that the proliferation of stem cells after sublethal irradiation remains the same, while higher rates of suicide are determined by the death of the precursors of the transitory colonies. At the same time higher proliferation of stem cells is not artifact in lethally irradiated animals and is also detectable after exclusion of the effects of the precursors of the transient colonies.

A study was of the influence of size-fractionated thymocytes in the density gradient of bovine serum albumin on the number of CFUs in the bone marrow of mice exposed to sublethal irradiation. Subject to separation were thymocytes obtained from intact mice and mice after multiple injections of dexamethasone (DM). Two cell populations were demonstrated during separation of thymocytes from intact mice. Injection of the first cell population brought about a decrease in the number of CFUs in the bone marrow during postradiation recovery, whereas injection of other thymocyte subpopulation resulted in an increase in CFUs. The use of thymocytes obtained from DM treated mice enabled the detection of an increase in bone marrow CFUs, induced by both unfractionated thymocytes and two fractions of thymocytes.

Some radiobiological characteristics of CBWA mice (e. g. response to gamma r and X-radiation and the radioprotective efficiency of 2-AT and AET were shown not to differ virtually from those of F1 hybrids (CBA X C57Bl/6). No essential differences were also found in radiosensitivity of the bone marrow cells of (CBA X C57Bl/6)F1 and CBWA mice in vitro and in situ. On the basis of the data obtained, the authors recommend CBWA mice for radiobiological experiments as well as hybrids (CBA X C57Bl/6)F1.

The rate and the degree of recovery of committed precursors of granulocytes and monocytes (CFUc) following long-term fractionated irradiation were a function of a cumulative radiation dose. In rats exposed to doses of 9.7 and 19.4 Gy the number of CFUc of myelokaryocytes and granulocytes of blood reached the control values after 1-3 months. The increase in CFUc of animals exposed to a dose of 29.1 Gy was transient and did not provide the recovery of granulocytopoiesis.

In experiments on 600 mice, relative biological effectiveness of tritium oxide was compared to that of gamma-radiation (137Cs) with respect to the response of CFUc. It was shown that RBE of tritium oxide was 1 within the dose range from 0.8 to 0.4 Gy.

The autoradiographic method was used to study proliferative activity of cells of a myeloid and erythroid compartments of the bone marrow of intact and irradiated (a single exposure of 10 Gy) rats. The proliferative activity and differentiation rate of cells decreased at early times after irradiation. It was shown that giant neutrophils had heavy tracer nuclei, were formed from myeloblasts, being at the most active phase of the S stage at the time of irradiation, and had a very low differentiation rate.

Cytochemical methods were used to study the activity of acid and alkaline phosphatases, neutral and acid nonspecific esterases, and peroxidase in the clones of stromal human marrow stromal fibroblasts at the 10th-12th day of cultivation with rabbit feeder. All the cells in the clones contained acid phosphatase. All the colonies had 5 to 90% of cells with positive response to alkaline phosphatase. The colony cells did not show any neutral and acid nonspecific esterases or peroxidase.

A study was made of the changes in the mode of interaction between T- and B-lymphocytes of mouse lymph nodes with respect to the phenomenon of inactivation of non-syngeneic haemopoietic stem cells. It was shown that irradiation of B-lymphocytes with doses of 77.4--232.2 mC/kg changes their helper activity into a suppressor activity with regard to T-cell-killers having a low electrophoretic mobility.

The effect of the colony-stimulating activity (CSA) on hemopoiesis in a long-term culture (4.5 week) of mouse embryonal liver was studied. After addition of the spleen cell-conditioned medium containing CSA to the organ culture, there was a decrease in the number of CFUs and in the granulocyte and macrophage precursors. However, the production of granulocytes and macrophages in the test cultures either did not fall or increased with primary differentiation of neutrophils. Addition of the medium with CSA shifted the equilibrium in the culture towards more intense production of differentiated cells at a lower level of the maintenance of precursors.

During local irradiation of the hind limb, the depleted hemopoietic tissue develops lymphocytosis which is largely due to the accumulation of thymic lymphocytes. T cells produce no effect on proliferative activity of hemopoietic precursor cells capable of colony formation on the spleens of lethally irradiated recipients. At the same time they stimulate the proliferation of erythroid cells, thereby accelerating the regeneration of erythropoiesis.

Tumorigenicity and anchorage independence in two types of the interspecies hybrids of the tumor and normal mammalian cells were studied. One hybrid type was derived from fusion of spontaneously transformed Chinese hamster and normal mouse cells; the second type was obtained by fusion of SV40-transformed Djungarian hamster and the same mouse cells. The tumorigenicity in the athymic nude mice was suppressed in the first type of hybrids. The hybrid clones derived from fusion of SV40-transformed and normal cells could form tumor in nude mice. Testing of hybrid clones for their ability to form colonies in soft agar showed that all hybrids grew well in the medium, similar to tumor parental cells. These data suggest that malignancy and anchorage independence are under separate genetic control. The influence of the origin of the tumor parental cells (spontaneous or SV40-virus transformation) on the expression of the malignancy in hybrids of the tumor and normal cells is discussed.

A cytophotometrical determination of DNA content was performed in cells of murine spleen colonies originating from bone marrow and in lymphocytes of axillary lymph nodes under various temperatures (22, 25 and 37 degrees C) of hydrolysis (5N HCl). It is shown that acid hydrolysis at 20 and 25 degrees C is most-preferable for proliferated cells of spleen clones and for non-proliferated lymphocytes. It is concluded that hydrolysis curves for clonal cell nuclei in different phases of mitotic cycle practically coincided.

The kinetics of the migration of the precursors of natural killer cells (NKC) from the bone marrow to the peripheral lymphoid organs has been studied. The total irradiation of C57BL/6 mice, BALB/c mice and (CBA X X C57BL/6)F1 hybrid mice in a lethal dose has been found to completely inhibit NKC. The partial protection of the bone marrow during irradiation leads to the complete regeneration of NKC in the spleen in 30-60 days. On the contrary, in the lymph nodes no NKC repopulation has been observed. The possible mechanisms of the migration of the precursors of NKC from the bone marrow are discussed. It is suggested that the precursors of NKC migrate from the bone marrow and finally differentiate into NKC in the spleen.

In this work a model is proposed describing inactivation of colony-forming haemopoietic stem cells as a function of time during long-term irradiation within a wide range of dose-rates (from 0.01 to 100 Gy/day). There was a good agreement between theoretical and experimental data on the number of stem cells altered by irradiation of mice within the indicated range of dose-rates. It was shown that specific rate of cell division increased and the duration of the mitotic cycle decreased (from 98 h to 7 h) with increasing dose-rate by 3, or more, orders.