Erythroid cells in immunoregulation: characterization of a novel suppressor factor.

Nucleated erythroid cells (EC) have been previously reported to possess a potent natural suppressor (NS) activity for B-cell responses. In this study, we demonstrate that murine EC are able to reduce not only lipopolysaccharide (LPS)-driven B-cell proliferation, but also proliferative and cytotoxic T-cell responses generated in a primary allogeneic mixed lymphocyte culture (MLC); and that a soluble low molecular weight factor may be involved in such EC-derived immunoregulation. In addition, the erythroid cell-derived suppressor factor (ESF) was found to be capable of effectively reducing the allergen-driven proliferation of peripheral blood mononuclear cells (PBMC) isolated from allergic patients.

[Effects of multipotent hematopoietic stem cell inhibitory factor on formation of immune response to viral antigen].

An immunostimulating effect of PIF was studied. The augmentation of antibody production to Coxsackie A13 virus as well as protective effect during influenza infection have been found out in mice after PIF injections. An immunostimulating effect of PIF after SRBC immunization of mice has been also revealed.

[Expression of erythroid differentiation antigens on mononuclear cells of peripheral blood in neoplastic progression of non-Hodgkin's malignant lymphoma].

High level expression of erythroid differentiation antigens on peripheral blood mononuclear cells associated with increased BFUe number has been identified in a malignant lymphoma patient. A possible pathogenetic role of such disturbance in leukemogenesis has been considered.

[The regulation of hematopoietic stem cell proliferation and differentiation (CFU-S) during antigenic exposure].

Hemopoietic stem cell (CFUs) proliferation is controlled by regulatory activities (stimulator and inhibitor) produced by bone marrow macrophages. Previously it has been shown that antigen administration stimulates CFUs proliferation. The data obtained in this study show the possible mechanism of antigen-induced stimulation of CFUs proliferation.

Species-nonspecific action of soluble immunosuppressive factor produced by murine immature erythroid cells.

Immature murine erythroid cells have natural suppressor cell activity suppressing in vitro mouse plaque-forming cell response and LPS-stimulated proliferative response of mouse spleen cells. A cell population enriched by erythroid precursors can produce a soluble activity with similar suppressive abilities. This erythroid suppressor activity (ErSF) has a low Mr (1 to 10 kDa).

[Erythroid immunosuppressor cells (Er suppressors) and their role in the regulation of immunity].

It is a review of works concerning the new mechanism of immunoregulation by immature erythroid cells (Er-suppressors). Er-suppressors producing humoral activity were shown to be capable of inhibiting B cell proliferation, production of immunoglobulins and humoral immune response both in mice and man. By certain characteristics Er-suppressors seem to be an logous to natural suppressors described by many authors.

[Suppressive effect of the blast cells of AKR strain mice on antibody formation in vivo and lymphocyte proliferation in vitro].

Blast cells obtained from the "erythropoietic spleen" of FG-stimulated young mice and cells accumulating in the spleens of preleukemic AKR mice have a marked suppressive effect on spontaneous and mitogen-induced proliferation of young mouse splenocytes in vitro and suppress the development of humoral immune response in immunized recipients during syngeneic transfer in vivo. Some disturbances in erythron system in preleukemic AKR mice manifested in the accumulation of immature erythroid precursors which are suppressors of immunocompetent lymphocytes are suggested to be a pathogenetic link in the development of leukemia.

[Interrelation of the dynamics of antigen intake into bone marrow and the proliferation of hematopoietic stem cells].

As it is previously shown (Tsyrlova et al., 1986), the level of humoral immune response is not only determined by the reaction of peripheral lymphoid system on antigenic effect, but also is bound up with the observed stem blood cell (SBC) proliferation in bone marrow (Frindel et al., 1976, Kozlov et al.

The effect of haemopoietic stem cell proliferation on the humoral immune response in mice.

A study was made of the effect of humoral factors, isolated from bone marrow cell (BMC) supernatant fluid and capable of modifying CFU-S proliferation, on the generation of IgM plaque-forming cells (PFC) against sheep red blood cells (SRBC) in mice after adoptive transfer. Adoptive transfer of BMC, preincubated with the humoral factor RBME-III, which stimulates CFU-S proliferation, was shown to suppress the splenic PFC generation in recipients; treatment of BMC with a further factor NBME-IV, which inhibits CFU-S proliferation, was followed by augmentation of PFC generation. Similar effects were obtained while studying the IgM PFC generation in the bone marrow of mice after secondary immunization when relevant factors were injected, in vivo, 24 hr following primary immunization.

[Proliferative activity of the hematopoietic stem cell in antigenically stimulated splenectomized mice].

Proliferative activity of hemopoietic bone-marrow stem cells has been studied in splenectomized mice in response to sheep red blood cells (2 X 10(8], pneumococcal polysaccharide (100 micrograms) and lipopolysaccharide E. coli (100 micrograms) injections. Spleen and its lymphoid cellular elements were shown to be of great importance for the regulation of the functional activity of hemopoietic stem cells under the antigenic influence.

Colony-forming activity of pluripotent stem cells in tolerant mice following antigen exposure.

The effect of sheep red blood cells (SRBC) and human red blood cells (HRBC) on the number of CFU-S in the bone marrow and spleen of (CBA X C57BL/6)F1 mice tolerant to SRBC was examined. The number of bone marrow and spleen CFU-S in SRBC tolerant mice was increased after injection of HRBC. After challenge with SRBC, CFU-S number was elevated in the spleen but not in the bone marrow.

[Colony-forming activity of hematopoietic stem cells in tolerant mice as affected by antigens].

The effect of sheep red blood cells (SRBC) and human red blood cells (HRBC) on the amount of CFUs in the bone marrow and spleen of (CBA X C57BL/6) FI SRBC-tolerant mice was studied. The increase in the number of bone marrow and spleen CFUs was demonstrated in SRBC-tolerant mice injected with HRBC. Using SRBC test injection the increase in CFUs amount was observed in the spleen, but not the bone marrow, where the amount of CFUs remained unchanged.

[Experimental model for studying the participation of bone marrow cells in antibody formation].

Participation of bone marrow cells in the production of IgM antibody forming cells (AFC) in the primary immune response to sheep red blood cells (SRBC) in C57Bl/6 and BDA/2 mice was studied. The animals of this line differed in sensitivity to preoral benz(a)pyren (BP) injection. After BP injection a toxical injury of bone marrow cells was observed for two days in DBA 2 mice but was not marked in C57Bl/6 mice.

[Effect of androgens on the development of leukemia in AKR-strain mice].

A possibility of the androgen's correction of spontaneous and transplanted leukogenesis has been investigated in AKR mice. Prolongation of life was observed in the animals treated with the hormone at early stages of the leukemia development. The obtained results may be related to the stem hemopoietic precursors differentiation change under the testosterone influence manifested by erythropoiesis stimulation and the reduction of granulocytic colonies determined by the growth in the cellulose-acetate membranes (CFUcam).

Hemopoietic stem cells "age" structure revealed by the exogenous colony forming method.

The number of colony forming units in mice following the transplantation of cells of bone marrow, spleen and embryonal liver, forming exogenous spleen colonies on 5, 8 and 11 days has been determined. It has been shown that stem cell subpopulation forming colonies on 5 day (CFUs-5) was notable for lower capacity for self maintenance, and contained predominantly by erythroid colonies, these CFUs-5 were mainly in embryonal liver and less in reduced in the hemopoietic populations in mice.

Hemopoietic stem cell proliferative activity in B-mice under the influence of antigenic stimulation.

The influence of thymus dependent and thymus independent antigens on proliferation of CFU-S in B-mice bone marrow was investigated. The process of CFU-S proliferative activity increases after the injection of both antigens and is mediated in part by B-lymphocytes.

[Immunodepressive effect of cell populations with varying erythropoietic activity in embryos and newborn mice].

The cells of liver from the 11-12 day old embryos and of spleen from newborn mice were transplanted to adult syngeneic recipients immunized by the ram erythrocytes. The immune response in the recipient spleens was estimated by the number of antibody-forming cells. The cells of embryonic liver and of newborn spleen suppressed the immune response in recipients to a great extent.

[Characteristics of the restoration of the hematopoietic microenvironment of the spleen regenerating after partial damage].

The initial stages of restoration of hemopoietic microenvironment in a regenerating spleen were studied functionally and morphologically after its partial damage. The hemopoietic microenvironment is restored locally and this process involves the damaged region only. The stages of restoration of hemopoietic microenvironment in the spleen are determined only by the properties of the spleen stroma itself and do not depend on the conditions of regeneration (in situ damage or ectopic transplantation).