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Biomedical subjects

G M Edelman

Publications and source records attributed to G M Edelman.

At least 325 records · Page 18Linked to original sources
PubMed1973

Characterization of splenic lymphoid cells in fetal and newborn mice.

In order to clarify the cellular events that precede the onset of immunological competence in the mouse, we have characterized and quantitated the lymphoid cells of the spleen as a function of age. Our results show that T cells and B cells both appeared in the spleens of Swiss-L mice as early as the 15th-16th day of gestation. Antigen-binding cells specific for each of three different antigens were also first detected during this same 24 h interval. The B cells and three varieties of antigen-binding cells increased in number rapidly and in parallel until about 1 wk after birth. The T cells, which were more numerous than B cells at first, increased in number somewhat more slowly. Coincident with the onset of response to antigen, there was a further increase in B cell numbers and a decrease in the T cell to B cell ratio. The capacity to respond to antigen by cellular proliferation and synthesis of antibody did not arise until about 2 wk after birth although there were no quantitative changes in the total numbers of T cells, B cells, and antigen-binding cells between 1 and 2 wk of age. Some qualitative change, such as the functional maturation of an antigen-reactive cell, may be required during this interval for the onset of this immunological response. Although the numbers of antigen-binding cells present in fetuses and young animals were smaller than in adults, we have as yet been unable to detect any restriction in the variety of specificities that can be expressed in fetuses, either in the kinds of antigens bound or in the range of avidities with which a single antigen is bound.

Age Factors↗
PubMed1973

Immunological functions of lymphocytes fractionated with antigen-derivatized fibers.

Specific antigen-binding cells from spleens of immune and nonimmune mice were isolated by the method of fiber fractionation. After removal from the fibers, these cells were assayed for their viability, their ability to rebind to fibers of the same specificity, and their in vivo response to the antigen after transfer to syngeneic irradiated recipients. These experiments indicate that the fiber method yields highly enriched populations of specific antigen-binding cells that are viable and include antigen-sensitive bone marrow-derived cells capable of undergoing mitosis and differentiating into antibody-secreting cells.

Animals↗
PubMed1973

Concanavalin A derivatives with altered biological activities.

Chemical derivatization of tetrameric concanavalin A (Con A) with succinic anhydride or acetic anhydride converts the protein to a dimeric molecule without altering its carbohydrate-binding specificity. At low concentrations, the dose-response curves for the mitogenic stimulation of mouse spleen cells by native Con A and succinyl-Con A are similar. Above lectin concentrations of 10 mug/ml, however, the response to Con A is diminished, while that for succinyl-Con A does not decrease until much higher doses are reached. We have attributed this difference mainly to the higher rate of cell death induced by the native Con A molecule. Con A also shows a greater capacity than succinyl-Con A to agglutinate sheep erythrocytes and to inhibit cap formation by immunoglobulin receptors on spleen cells. Moreover, at low concentrations, Con A induced its glycoprotein receptors to form caps, but succinyl-Con A did not induce cap formation. Addition of antibodies directed against Con A to succinyl-Con A bound on cells restored the properties of agglutination, inhibition of immunoglobulin receptor cap formation, and induction of cap formation by Con A receptors. Similar results have been obtained for acetyl-Con A. These data suggest that the altered biological activities of succinyl-Con A and acetyl-Con A are attributable to their reduced valence.

Acetates↗
PubMed1973

Receptor mobility and receptor-cytoplasmic interactions in lymphocytes.

An analysis of the inhibition by concanavalin A of the mobility of lymphocyte surface receptors is used to construct an hypothesis on membrane receptor-cytoplasmic interactions. It is proposed that binding of multivalent lectins alters the interaction of an assembly of colchicine-binding proteins with lectin receptors and other receptors, and reciprocally that the state of the colchicine-binding assembly alters the mobility and distribution of surface receptors on the cell membrane. Observations of the effect of colchicine and related drugs on the inhibition of receptor mobility by concanavalin A lend support to this hypothesis. The proposed model has several implications for studies of the initial events of mitogenesis in lymphocytes as well as for cell-cell interactions in general.

Colchicine↗
PubMed1973

Chemical dissection of mammalian spermatozoa.

Spermatozoa from several mammalian species have been dissected by chemical methods to yield free heads, tails with attached midpieces, and tails from which the mitochondrial components of the midpiece were removed. Mouse and rat spermatozoa were cleaved by brief treatment with trypsin to yield free heads and tails, while human, guinea pig, and rabbit spermatozoa were cleaved by trypsin only after incubation with 2-mercaptoethanol or dithiothreitol. Spermatozoa were also cleaved at the junction of the head and the tail by treatment with acid and base. Mitochondria were removed from intact spermatozoa or isolated tails by mechanical shear after treatment with 2-mercaptoethanol or dithiothreitol. The dissected components of spermatozoa were fractionated with good yield and high purity by density gradient centrifugation. Ultrastructural analysis indicates that proteolytic cleavage to yield separated heads and tails occurs at a specific location in the neck of the spermatozoon, leaving the basal plate attached to the head of the cell. In contrast, after acid cleavage the basal plate remains with the midpiece. Proteolytic treatment has no apparent effect on any other spermatozoan structures, whereas acid or base treatment results in damage to the plasma membrane, the acrosome, and other structures. The specificity of the proteolytic cleavage suggests that a particular protein or group of proteins may be responsible for the linkage between the sperm head and tail.

Animals↗
PubMed1972

Binding of thymus- and bone marrow-derived lymphoid cells to antigen-derivatized fibers.

Thymus-derived lymphocytes (T cells) and bone marrow-derived lymphocytes (B cells) from mouse spleens bind specifically to antigen-derivatized nylon fibers. The fiber-bound population consisted of about 60%-70% B cells and 30% T cells as determined by cytotoxicity, fluorescence, and antibody-complement binding assays. Essentially all fiber-bound cells were viable and could be accounted for as T or B cells. Enriched populations of T or B cells could be isolated on the fibers by destruction of one or the other cell type with the appropriate antiserum plus complement. T or B cells could also be fractionated according to their relative affinity (or avidity) for a given antigen.

Animals↗
PubMed1972

Restriction of the mobility of lymphocyte immunoglobulin receptors by concanavalin A.

The induction by anti-immunoglobulin of patch and cap formation on mouse lymphocytes was inhibited by the addition of concanavalin A. This effect was reversed by alpha-methyl-D-mannoside, a competitive inhibitor of the binding of concanavalin A. Concanavalin A prevented both patch and cap formation, in contrast to the metabolic inhibitor NaN(3), which prevented only cap formation. This suggests that binding of concanavalin A induces changes on or in the lymphocyte membrane that inhibit free diffusion of immunoglobulin receptors.

Animals↗
PubMed1972

Specific fractionation of immune cell populations.

Antigen-binding cells from spleens of immune and nonimmune mice were isolated by the method of fiber fractionation. Binding of the lymphoid cells to derivatives of nylon fibers made with various antigens was prevented by the presence of the respective free antigen, as well as by antibodies to mouse immunoglobulins. Antigen-binding cells specific for dinitrophenyl groups were separated from direct and indirect plaque-forming cells of the same specificity. Spleen cells from immune and nonimmune animals were fractionated according to their relative affinities for antigen, and the percentage of antigen-binding cells in the spleens of nonimmune animals was estimated. A comparison of the numbers and relative affinities of immunoglobulin receptors of immune and nonimmune populations indicated that after immunization only those antigen-binding cells of higher affinities were increased in number. This finding suggests that the specificity of clonal selection depends not only upon the binding of antigen to a lymphoid cell but also upon the capacity of that cell to be triggered to mature and replicate.

Animals↗
PubMed1972

2 -Microglobulin--a free immunoglobulin domain.

Analysis of the primary structure of beta(2)-microglobulin indicates that this human protein is homologous in sequence to the constant portion of immunoglobulin light chains (C(L)), and to the homology regions (C(H)1, C(H)2, and C(H)3) of the constant portion of gamma1 (heavy) chains of immunoglobulin G. Homology with the C(H)3 region is particularly striking. No convincing homology could be demonstrated by similar comparisons with the variable regions of immunoglobulin light and heavy chains. beta(2)-Microglobulin contains an intrachain disulfide loop of 57 amino-acid residues that is similar in size to disulfide loops found in the constant regions of immunoglobulin G. These findings suggest that beta(2)-microglobulin is a free immunoglobulin domain, possibly serving an effector function similar to that of the C(H)3 domain of gamma1 chains of immunoglobulin G.

Amino Acid Sequence↗