Brain-associated stem cell antigen: an antigen shared by brain and hemopoietic stem cells.

There is an antigen on mouse brain tissue which is shared by the hemopoietic colony-forming unit or stem cell of the mouse. Treatment of bone marrow or fetal liver cells with anti-brain antisera inhibits expression of colony-forming units. The anti-stem cell antibody is not absorbed by thymus cells and thus can be distinguished from the anti-thymocyte antibody which these antisera also contain.

Immunological tolerance to a hapten. I. Induction and maintenance of tolerance to trinitrophenyl with trinitrobenzene sulfonic acid.

Treatment of mice with a nonimmunogenic preparation of free reactive hapten, trinitrobenzene sulfonic acid (TNBS), leads to the induction of a state of tolerance to the hapten, 2,4,6-trinitrophenyl (TNP). This is determined by the lack of response to the haptenic moiety in an immunogenic hapten-carrier conjugate (TNP-SRBC) as assayed both by serum antibody titrations and the hemolytic plaque assay. The tolerance produced is specific for the hapten, since the anticarrier responses are essentially unaltered compared with the control values. The unresponsiveness induced by TNBS treatment is a dose-dependent phenomenon, becoming less complete at lower doses of TNBS. The tolerance is of a definite length, both in its induction phase and in the duration of the established unresponsive state. Tolerance can be maintained and extended, and may also be reentered once escape has been initiated.

Antigenic differences between hemopoietic stem cells and myeloid progenitors.

Bone marrow contains pluripotent stem cells which give rise to colonies when injected into irradiated syngenic hosts as well as more differentiated progenitor cells of the myeloid cell which are able to form colonies in vitro. Antisera against brain is known to contain antistem cell antibody. The present experiments were designed to determine if the myeloid progenitor cell still expresses the stem cell antigen. Bone marrow cells were treated with antibrain antiserum plus complement and then survival of stem cells was determined by injection into irradiated hosts. Survival of myeloid progenitor cells was determined by culturing the cells in vitro. It was found that stem cells were eliminated by the antiserum but that myeloid progenitors were not. Inefficient in vitro lysis was ruled out as the reason for this difference since in vitro colonies were not reduced when the cells were treated with anti-immunoglobulin or after passage through an irradiated host. In the differentiation from stem cell to myeloid progenitor there is an associated surface antigen change.

Leukemia in AKR mice. I. Effects of leukemic cells on antibody-forming potential of syngeneic and allogeneic normal cells.

Cells from the spleen, thymus, lymph node, and liver of leukemic AKR mice suppress in vitro antibody responses of normal syngeneic and semiallogeneic cells. This suppression can be mediated by irradiated leukemic cells, requires cell contact between leukemic and normal cells, and may occur at any time during the in vitro culture period. Leukemic AKR cells do not suppress antibody responses of allogeneic cells, even when allogeneic cells have H-2 or background genes homologous with AKR. Leukemic cells do, however, suppress cells that are unable to respond allogeneically to leukemic AKR cells, such as cells of the F1s of AKR. Suppression of normal AKR antibody responses by leukemic AKR cells may be overcome by addition of irradiated allogeneic cells. The fact that leukemic AKR cells are able to suppress normal lymphocyte responses may be of significance in pathogenesis of leukemia in these mice.

Human CD4 binds immunoglobulins.

T cell glycoprotein CD4 binds to class II major histocompatibility molecules and to the human immunodeficiency virus (HIV) envelope protein gp120. Recombinant CD4 (rCD4) bound to polyclonal immunoglobulin (Ig) and 39 of 50 (78%) human myeloma proteins. This binding depended on the Fab and not the Fc portion of Ig and was independent of the light chain. Soluble rCD4, HIV gp120, and sulfated dextrans inhibited the CD4-Ig interaction. With the use of a panel of synthetic peptides, the region critical for binding to Ig was localized to amino acids 21 to 38 of the first extracellular domain of CD4. CD4-bound antibody (Ab) complexed with antigen approximately 100 times better than Ab alone. This activity may contribute to the Ab-mediated enhancement of cellular HIV interaction that appears to depend on a trimolecular complex of HIV, antibodies to gp120, and CD4.

[Radial asymmetric keratotomy in mild-degree myopia]. / Radial'naia asimmetrichnaia keratotomiia pri miopii slaboi stepeni.

The suggested method for surgical correction of weak myopia involves two mutually perpendicular incision on the cornea in the major meridians. These two incisions result in but a slight alteration of the tissues, and a stable refraction effect of about 1.5 diopters is achieved at once; vision acuity improves to make 0.9-1.0.

Functional development of the interacting cells in the immune response. III. Role of the neonatal spleen.

Neonatal splenectomy and congenital absence of the spleen were shown to be associated with lack of primary IgM antibody synthesis, deficient bone marrow-thymus cell synergism. altered mitogen responsiveness and depressed homing patterns of thymocytes to the spleen. Using congenitally asplenic animals, altered B-T cell cooperation was manifest at the T cell but not B cell level. This correlated with the ability of thymus cells from either congenitally asplenic or neonatally splenectomized (NSx) animals to respond to the B cell mitogen lipopolysaccharide although there were no detectable Ig=ells present. To determine the role played by the spleen in the development of T cell function, NSx animals were given either irradiated or normal spleen grafts. Both irradiated and unirradiated grafts restored normal B-T cooperation and normal mitogenic responses of thymus cells. However, neither type of spleen graft was successful in restoring normal homing patterns to the spleen. It is concluded that the splenic microenvironment influences T cell maturation very early in life and that only some of the effects attributable to the absence of the spleen can be reversed by the reintroduction of this tissue as a graft.

Cell surface DNA in immunosuppression in AKR leukemia.

Spleen cells from leukemic AKR mice contain nonspecific T suppressor cells that suppress the in vitro anti-SRBC responses of normal AKR spleen cells. The suppression is abrogated by pretreatment of the leukemic cells with DNase. Cells with surface DNA can be enriched by treatment with anti-DNA antibodies and removed on anti-Ig columns. Even though there is a 10-fold enrichment in suppression by the surface DNA-positive cells (DNA+), the depleted population (DNA-) still suppresses with an efficiency comparable to the unfractionated spleen cells. Pretreatment with anti-I-J antiserum and separation on columns neither enriches nor depletes suppressor cells. Fractionating leukemic spleen into 4 populations of cells by sequential treatment with anti-DNA and anti-I-J with separation on appropriate columns, resulting in 4 populations (DNA+/I-J-, DNA+/I-J+, DNA-/I-J+, and DNA-/K-J-), revealed that the DNA+/I-J- cells that comprise ca. 15% of the total are the most potent suppressors. The DNA+/I-J+ cells that comprise ca. 2% of the cells are less efficient and their suppression is not sensitive to DNase. The DNA-/I-J+ population (ca. 10% of the total) are also poor suppressors. The remaining cells, which are DNA-/I-J-, do not act as suppressors. When small numbers of any 2 of the 4 fractions were added together, it was found that the DNA+/I-J- cell can interact with the DNA+/I-J+ and the DNA-/I-J+ cells but not the DNA-/I-J- cells to give enhanced suppression.

Two distinct events in lineage establishment of a biopotential hemopoietic cell line.

HL-60, a human myelomonocytic cell line can be induced to differentiate along either granulocyte or monocyte pathways and therefore is a good model to study lineage establishment. We have shown that there are two classes of reactions in the establishment of the granulocytic line distinguishable by their kinetics. The fast reaction occurs in hours and is induced by ouabain or A23187, agents which effect ions. The slow reactions occur at a constant rate over a period of 5 days and are induced by the surrogate inducers RA and D3 but also by the natural inducer GM-CSF. GM-CSF induces the enzyme markers which we use to characterize both granulocytes and monocytes in the same cell. If these markers are indeed unique to each of the lines this means that HL-60 has both gene programs initiated by GM-CSF and D3. Variant lines which do not respond to one or more of the inducers can be used to analyze this point since variants which are induced only to granulocytes or only to monocytes by GM-CSF have been isolated.

Leukemia in AKR mice: a defined suppressor cell population expressing membrane-associated DNA.

Leukemic AKR mouse spleen cells suppress normal AKR anti-sheep erythrocyte antibody responses in vitro. Treatment of leukemic spleen cells with DNase I prior to coculture with normal AKR cells abrogates their suppressive ability. Treatment of leukemic cells with a wide range of DNase I concentrations has no effect on the viability of these cells as measured by incorporation of [(3)H]thymidine or by eosin dye exclusion. When the activating divalent cations required for DNase I action are functionally removed in the enzyme treatment medium by chelation with EDTA, the ability of DNase I to abrogate suppression is abolished. Furthermore, the effects of DNase I in overcoming suppression are not able to be mimicked by trypsin, Pronase, or ribonuclease. These results are consistent with the existence of a population of cells in the leukemic spleen that expresses a form of membrane-associated DNA that functions in the suppression of normal antibody responses. The existence of such a population was shown by treating leukemic spleen cells with anti-single-stranded-DNA and then passing them through an anti-immunoglobulin immunoadsorption column. Approximately 15% of the leukemic cells are retained on the column and can be specifically eluted with the normal immunoglobulin. The cells of this enriched population when cocultured with normal spleen cells exhibit a 10-fold greater suppressive ability than unfractionated cells. Thus, there exists in the spleens of overtly leukemic AKR mice a population of cells expressing a form of DNA on their surfaces that in some manner is necessary for immunosuppression.

Development of a quantitative immunological assay for the study of spore coat synthesis and morphogenesis.

A quantitative assay employing (125)I-labeled antibody has been developed for Bacillus cereus T spore coat protein. Populations of antibody molecules with various affinities for inner or outer coat can be prepared by selective adsorption to and elution from different coat preparations. Adsorption to and elution from intact spores results in an antibody preparation at least 15 times more reactive to outer coat. This antibody is useful for measuring the time and extent of spore coat maturation, i.e., outer spore coat formation. Rifampin inhibits the increase in content of this coat antigen.

Retinoic acid inhibition of transplasmalemma diferric transferrin reductase.

All trans retinoic acid inhibited diferric transferrin reduction by HeLa cells. The NADH diferric transferrin reductase activity of isolated liver plasma membranes was also inhibited by retinoic acid. Retinol and retinyl acetate had very little effect. Transplasma membrane ferricyanide reduction by HeLa cells and NADH ferricyanide reductase of liver plasma membrane was also inhibited by retinoic acid, therefore the inhibition was in the electron transport system and not at the transferrin receptor. Since the transmembrane electron transport has been shown to stimulate cell growth, the growth inhibition by retinoic acid thus may be based on inhibition of the NADH diferric transferrin reductase.