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Biomedical subjects

E S Vitetta

Publications and source records attributed to E S Vitetta.

At least 289 records · Page 16Linked to original sources
PubMed1978

Blocking of primary in vitro antibody responses to thymus-independent and thymus-dependent antigens with antiserum specific for IgM or IgD.

The effect of anti-mu and anti-delta on the primary in vitro IgM response of murine splenocytes to thymus-dependent (trinitrophenylated erythrocytes) and thymus-independent (trinitrophenylated brucella) forms of trinitrophenyl was studied. The results indicate that either anti-mu or anti-delta can block the response of adult splenocytes to the thymus-dependent antigen. The thymus-dependent responses of neonatal splenocytes that bear a low concentration of IgD were also abrogated by treatment with anti-delta. In contrast, anti-mu, but not anti-delta, blocked the response of adult splenocytes to the thymus-independent antigen used. These results indicate that both IgM and IgD are receptors required for triggering cells by a thymus-dependent antigen but that only IgM receptors are required for triggering by the thymus-independent antigen used.

Animals↗
PubMed1978

Inactivation of antigen-responsive clones with antisera specific for IgM or IgD.

The present study examines the isotype of cell surface immunoglobulins involved in triggering a response to thymus-dependent and thymus-independent antigens. Antibodies to immunoglobulin isotypes were used to block the in vitro interaction of receptor IgD and IgM with antigen. The results indicate that both IgD and IgM are necessary to trigger a response to TNP-SRBC but that only IgM is required for responsiveness to TNP-Brucella. Limiting dilution studies indicate that the inhibition of the immune response by antibody occurs at the level of precursor activation and suggest that there is no effect of antibody on subsequent proliferation of the daughter cells.

Animals↗
PubMed1978

Characterization of a B cell defect in the NZB mouse manifested by an increased ratio of surface IgM to IgD.

In an effort to define the cellular basis of abnormalities in polyclonal B cell activation previously noted in NZB mice, the surface immunoglobulin (sIg) isotypes of spleen cells from NZB mice were examined. After lactoperoxidase-catalyzed radioiodination, the cell surface immunoglobulins were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Spleen cells from 8- to 10-week-old NZB mice were found to have an increased ratio of cell surface IgM/IgD compared to cells from 11 control strains. The altered ratio of sIg isotypes was not a consequence of increased proteolytic activity present in NZB cell suspensions or of the presence of cytophilic antibody or autoantibody. Ontogenetic studies of the sIgM/sIgD (mu/delta) ration on splenocytes from NZB and BALB/c mice revealed that the former cells had higher mu/delta ratios as early as 2 weeks after birth. By 4 weeks of age the mu/delta ratios were equivalent. Between 4 weeks and 1 year of age, the mu/delta ratios on NZB splenocytes remained constant whereas those on BALB/c splenocytes decreased and reached adult levels at 6 weeks.

Animals↗
PubMed1978

Differentiation of bone marrow-derived lymphocytes.

Murine lymphocytes were enzymatically radioiodinated and the class of immunoglobulin (isotype) on the cell surface was studied as a function of differentiation and ontogeny. The results indicate that IgM is the first isotype to appear and that IgD is subsequently acquired. A proportion of IgM-bearing cells also bear IgD. The acquisition of IgD does not appear to be under the influence of the thymus or of exposure to antigen. The observations suggest a sequence of differentiation steps in which B-cells first express IgM then acquire IgD (to become "double bearers"), and eventually lose IgM. The relationship of the IgD-bearing cells to the IgG-bearing memory cells has not yet been established. The implications of these findings with regard to function and genetic organization are discussed.

Animals↗
PubMed1978

Cell surface immunoglobulin XXI. appearance of IgD on murine lymphocytes during differentiation.

The differentiation of Ig-bearing lymphocytes in adult mice was studied by monitoring the appearance of IgD relative to IgM on the surface of splenocytes obtained from lethally irradiated animals reconstituted for various periods of time with adult bone marrow cells, neonatal splenocytes, or Ig- adult splenocytes. It was found that IgM appears before IgD on differentiating lymphocytes. Furthermore, the rate of appearance of IgD during differentiation of adult cells is similar to that observed with neonatal cells.

Animals↗
PubMed1978

Labeling characteristics and separation of Ia antigen subunits.

Experiments with biosynthetic incorporation of 3H-amino acids into murine and guinea pig Ia antigens have indicated that these antigens consist of two polypeptide chains of 33,000 and 25,000 daltons, respectively, occasionally linked by disulfide bonds into a 58,000 dalton molecule. In contrast, studies with lactoperoxidase-catalyzed radioiodination have indicated that these Ia antigens consist of only a single chain of 25,000 daltons. We therefore undertook a study to explore the basis of these discrepant results. Since 3H-tyrosine labeled both chains well, the lack of tyrosine residues in the 33,000 dalton chain could not be the explanation for the lack of radioiodination. However, by partially purifying the Ia antigen preparation with Lens culinaris (lentil) lectin affinity chromatography before immunoprecipitation and by increasing the resolution of analysis by using discontinuous-SDS polyacrylamide gel electrophoresis, it was possible to show that the 33,000 dalton chain was in fact radioiodinated, though still poorly so relative to the 25,000 dalton chain, and that a radioiodinated 58,000 dalton molecule could be detected. These experiments suggest that the 25,000 dalton chain is more exposed to the external cellular environment, and thus more readily iodinated by lactoperoxidase. In addition, the studies indicate that the choice of labeling method, purification procedures, and analytical methods must be taken into account when interpreting experimental results.

Animals↗
PubMed1978

Structural studies on protein products of murine chromosome 17. III. Partial amino acid sequence of an H-2Kq molecule.

Twenty-one of the amino terminal twenty-seven amino acid residues have been assigned in the murine H-2Kq molecule and several additional assignments and corrections have been made in both the H-2Kk and H-2Kb molecules. The study shows that 1) H-2Kk and H-Kq, which are serologically related, have an identical amino acid sequence for all twenty positions that can be compared, 2) the H-2Kk and H-2Kq molecules differ from H-2Kb at only two positions--9 and 22, and 3) the additional sequence data on the H-2Kk, -Kb, and -Kq molecules increases the already striking homology between murine and human transplantation antigens.

Amino Acid Sequence↗
PubMed1978

Relationship between trinitrophenol and H-2 antigens on trinitrophenyl-modified spleen cells. III. Quantitative aspects of trinitrophenol binding on cells treated with trinitrobenzene sulfonic acid.

Splenic lymphoblasts or normal spleen cells were treated with varying concentrations of TNBS in order to assess whether cell membrane H-2 molecules were derivatized with TNP. Cells treated with high concentrations of TNBS had their cell membrane H-2 molecules derivatized and functioned antigenically as inhibitors in a cold target TNP-CML competition assay. In contrast, cells derivatized with lower concentrations of TNBS had a significant proportion of their membrane proteins derivatized with TNP but did not have their H-2 molecules derivatized. These latter cells were unable to block anti-TNP cytotoxic effector cells in the competition assay. When cells were treated with 3H-TNBS, it was observed that TNP couples to cell membrane H-2, Ia and Ig molecules, and an estimate of the number of TNP molecules bound per cell at varying concentrations of TNBS was determined. The data obtained are consistent with there being a requirement for TNP to directly derivatize H-2 molecules on the cell membrane in order to create antigenic determinants that can be recognized by cytotoxic anti-TNP effector cells. As an alternative, there may be a requirement for the presence of a high density of TNP molecules per cell rather than direct H-2 derivatization by TNP in order to account for activity.

Animals↗
PubMed1978

Structural studies on the murine IA alloantigens. II. Molecular weight characterization of the products of the I-A and I-E/C subregions.

Murine splenocytes were radiolabeled with 3H- and 14C-amino acids; the Ia alloantigens encoded by the I-A and I-E/C subregions were isolated by immunoprecipitation and analyzed for structural variation by polyacrylamide gel electrophoresis. The I-A subregion products (k, d, and b haplotypes) are composed of two polypeptides, alpha and beta, with m.w. of 34,000 and 26,000 daltons, respectively. Haplotype-associated differences in m.w. were detected in the I-E/C products of the k, r, p, and d haplotypes. The alpha and beta chains of E/Ck and E/Cr are 34,000 and 28,000 daltons, respectively; E/Cp and E/Cd molecules are composed of 31,000 and 29,000 dalton polypeptides. Thus, there is both subregion (I-A vs I-E/C) and haplotype (E/Ck, E/Cr vs E/Cd, E/Cp) associated variation in the m.w. of the Ia alloantigens. Additionally, the covalent vs noncovalent association of the Ia subunits was examined and it was found that the alpha and beta chains of both I-A and I-E/C are not covalently associated. However, the I-A alpha and beta chains tend to associate through disulfide bonds during detergent lysis; the presence of alkylating agents during cell lysis prevents this association, and only free alpha and beta chains are observed under nonreducing conditions.

Animals↗
PubMed1977

B-cell tolerance. IV. Differential role of surface IgM and IgD in determining tolerance susceptibility of murine B cells.

During ontogeny IgD appears later than IgM on splenocytes of neonatal mice (1) and at a time when mice develop a markedly increased immune responsiveness (2). Based on these observations, it was suggested that IgD serves as a "triggering" isotype for induction of immune responses, whereas surface IgM functions as a tolerizing receptor (3). To test this hypothesis, the susceptibility of adult splenocytes (which are predominantly mu(+)delta(+)[4-6]) and neonatal splenocytes (which bear predominantly IgM [mup(+); 1, 4-6]) to tolerance induction were compared. The results indicate that neonatal splenic B cells responsive to thymus dependent (TD) antigens are exquisitely susceptible to tolerance induction compared with those from adult mice (7-9). However, cells from both adult and neonatal mice were highly susceptible to tolerance induction when thymus independent (TI) antigen was used as immunogen (8). These results suggest that the major precursor for the TD response is a mu(+)delta(+)-cell which appears late in ontogeny and is resistant to tolerance induction and that the mup(+)-cell is the major precursor for the TI response and is highly susceptible to tolerance induction. Other differences between responders for TI and TD antigens have been described previously (10-12). To test this concept, adult splenocytes were treated with papain under conditions in which IgD, but not five other surface molecules, was removed (13). Such treated splenocytes were shown to be markedly susceptible to tolerance induction, resembling TD responders from neonatal animals. This experiment was interpreted as indicating that IgD confers resistance to tolerance induction on mu(+)delta(+)-cells. To prove this interpretation, it is necessary to show that specific removal of IgD with anti-delta also results in increased susceptibility to tolerance induction and that treatment with anti-mu does not have a similar effect. In the present studies, we have removed surface IgM or IgD by antibody-induced capping and assessed the tolerance susceptibility of the treated cells. Our results demonstrate that removal of IgD, but no IgM, from TD responders increases their susceptibility to tolerance induction.

B-Lymphocytes↗
PubMed1977

B-cell tolerance. III. Effect of papain-mediated cleavage of cell surface IgD on tolerance susceptibility of murine B cells.

Under defined conditions, papain removes IgD from cells while leaving IgM, H-2, Ia, Lyb-2, and complement receptor intact. The effect of such treatment with papain on the induction of tolerance in murine splenic B cells was determined in an in vitro system. Treatment of the cells with papain has no effect on subsequent antibody responsiveness presumably because surface receptors regenerate before and during incubation with immunogen. Removal of increasing amounts of IgD results in increasing susceptibility of thymus-dependent responsive cells to tolerance induction. The tolerance susceptibility of thymus-independent responsive cells, which we have previously suggested are immature cells that bear only IgM, is unaffected by cleavage of IgD. If cells are incubated for 24 h after treatment with papain, cell surface IgD and tolerance resistance return. These results indicate that a surface molecule affects susceptibility of B cells to induction of tolerance and suggest that this molecule may be IgD.

Animals↗
PubMed1977

Cell surface immunoglobulin. XX. Antibody responsiveness of subpopulations of B lymphocytes bearing different isotypes.

Murine spleen cells were depleted of specific B-cell subpopulations bearing different immunoglobulin isotypes by means of complement-mediated cytolysis after treatment with antisera specific for micron- and gamma-chains. The functional effect of this depletion was measured by assaying both the primary and secondary plaque-forming cell responses of the residual cells after transfer to carrier-primed lethally irradiated hosts. The results suggest that cells bearing IgM are the progenitors of plaque-forming cells in the primary response and cells bearing IgG are the major progenitors of IgG plaque-forming cells in the secondary response. The quantity of IgM on progenitors of secondary IgM plaque-forming cells decreases markedly as the interval between primary immunization and antigenic challenge increases. Long-term memory cells for the secondary IgM response bear small amounts of both IgM and IgG.

Animals↗
PubMed1977

The relationship between surface immunoglobulin isotype and immune function of murine B lymphocytes. I. Surface immunoglobulin isotypes on primed B cells in the spleen.

We investigated the ability of IgM-, IgD-, and IgG-bearing cells from the spleens of (BALB/c x C57BL/Ka)F1 mice primed to dinitrophenyl-bovine serum albumin (DNP-BSA) to restore the adoptive secondary anti-BSA and anti-DNP antibody responses. A rabbit anti-mouse IgD antiserum was prepared and the specificity documented by radioimmunoprecipitation, and cell surface staining. Purified populations of IgM-, IgD-, and IgG-bearing cells were prepared by immunofluorescent staining with isotype-specific reagents, and sorting on the fluorescence activated cell sorter. Bright or dull cells were transferred to irradiated syngeneic recipients which were challenged with DNP-BSA in saline. Unfractionated spleen cells restored an adoptive secondary serum antibody response which was all IgG (2-mercaptoethanol resistant). Purified IgM- or IgD-bearing cells restored both the secondary IgM and IgG antibody response. IgG-bearing cells restored only the IgG response. In addition, the IgG-bearing cells appear to suppress the adoptive secondary IgM response, since depletion of IgG-bearing cells from transferred spleen cells results in a marked increase in the adoptive IgM response.

Animals↗
PubMed1977

The relationship between surface immunoglobulin isotype and immune function of murine B lymphocytes II. Surface immunoglobulin isotopes on unprimed B cells in the spleen.

We investigated the ability of IgM-, IgD-, and IgG-bearing cells from the spleens of unprimed (BALB/c x C57BL/Ka)F1 mice to restore the adoptive primary anti-BSA and anti-DNP antibody responses. Purified populations of isotype-specific cells were prepared by immunofluorescent staining and sorting on the fluorescence activated cell sorter. Bright or dull cells were transferred to irradiated syngeneic recipients which were challenged with DNP-BSA in complete Freund's adjuvant. Unfractionated spleen cells as well as IgM- and IgD-bearing cells restored the adoptive primary IgM and IgG antibody response. IgG-bearing cells restored a vigorous adoptive response which was all IgG (2-mercaptoethanol resistant). Depletion of IgG-bearing cells markedly increased the adoptive IgM response, and depletion of IgM-bearing cells markedly increased the IgG response. However, depletion of IgD-bearing cells resulted in a considerable reduction in the IgG response. The latter finding indicates that there is a subpopulation of IgD-bearing cells which express little or no surface IgM and which make a considerable contribution to the adoptive primary IgG response.

Animals↗