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Biomedical subjects

L Hood

Publications and source records attributed to L Hood.

At least 307 records · Page 17Linked to original sources
PubMed1984

Molecular characterization of the recombination region of six murine major histocompatibility complex (MHC) I-region recombinants.

Using Southern DNA hybridization techniques, restriction enzyme site polymorphisms have been used to correlate the molecular maps of the murine major histocompatibility complex (MHC) I region with the genetic map derived from analyses of recombinant mouse strains. The data indicated that the DNA that maps between the I-A and I-E subregions is limited to 3.4 kilobases (kb) and includes the 3' end of the E beta gene. According to classical genetic mapping by recombinational analysis of serological markers, this region should encode the I-B and I-J subregions. These observations are surprising in two respects. First, 3.4 kb is a small amount of DNA to encode even one complete murine gene. Second, this region, which putatively encodes the I-J gene, appears to reside at least partially within the E beta gene. To analyze these apparent paradoxes, further, we cloned the 3.4-kb region in question from six I-region combinant strains [B10.A(3R), B10.a(5R), B10.A(4R), B10.GD, B10.HTT, and B10.S(9R)] and four strains used in the derivation of the recombinants (B10.D2, B10.A, C57BL/10, and ASW) into a lambda phage vector. By direct restriction enzyme mapping of polymorphic sites, we have confirmed the previously identified boundaries of the I-A and I-E subregions and have narrowed the estimate of the distance between these subregions to approximately 2.0 kb of DNA. This 2.0-kb region encompasses part of the intron between the first- (beta 1) and second-domain (beta 2) exons and the second-domain exon (beta 2) of the E beta gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Immunologic memory to phosphocholine. IV. Hybridomas representative of Group I (T15-like) and Group II (non-T15-like) antibodies utilize distinct VH genes.

The anti-phosphocholine (PC) memory response elicited in BALB/c mice by phosphocholine-keyhole limpet hemocyanin (PC-KLH) contains two groups of antibodies distinguished by their fine specificity for PC and p-nitrophenylphosphocholine (NPPC). Group I antibodies are inhibited by both PC and NPPC, while Group II antibodies are inhibited appreciably only by NPPC; only Group I antibodies are dominated by the T15 idiotype. Anti-PC hybridomas representative of the memory response to PC-KLH were produced to examine the variable region genes expressed by memory B cells. Two IgM hybridomas were of the Group I type, because they were inhibited by both PC and NPPC and they bound to the pneumococcus R36A. However, only one of these antibodies (PCM-2) expressed a T15 idiotope, while the other (PCM-1) did not express any of three T15 idiotopes. Despite its negative T15 idiotype profile, N-terminal amino acid sequencing of PCM-1 purified heavy chain and Southern blots of the hybridoma DNA indicated that it utilizes the T15 VH and JH1 genes. Three hybridomas, IgG1, IgM, and IgE, typical of Group II antibodies, were examined; these were negative for three T15 idiotopes and displayed measurable avidity only for NPPC in a PC-protein binding inhibition assay. These three hybridoma antibodies, like serum Group II IgG1, did not measurably bind to the bacterium R36A. The heavy chain amino termini of all three of these antibodies were inaccessible for Edman degradation. Southern blots of DNA from the IgG1 hybridoma revealed the T15 VH gene to be in the germ line configuration only and unassociated with any JH segment, indicating that this Group II antibody utilizes a VH gene different from the T15 family. These results signify that, whereas some diversity of the (anti-PC) memory response may be generated by somatic diversification of variable regions important in the primary response, a significant contribution to the overall heterogeneity of memory antibodies originates in the expression of additional variable region genes.

Amino Acid Sequence↗
PubMed1984

Immunologic memory to phosphocholine. V. Hybridomas representative of group II antibodies utilize V kappa 1-3 gene(s).

The anti-phosphocholine (PC) memory response of BALB/c mice to PC-KLH contains two groups of antibodies distinguished by fine specificity and by expression of the T15 idiotype that dominates Group I but not Group II anti-PC antibodies. The contribution of V kappa genes to this diversity was investigated by the analysis of L chains from PC-binding hybridoma proteins (PCBHP) representative of Group I and Group II. N-terminal amino acid sequence analysis was performed on the L chains of three independently derived Group II PCBHP up to residue 23 (PCG1-1) or 21 (aPC-111-1 and aPC-12-3). These three sequences differed from each other by only one or two residues, but differed by approximately 50% from the L chains of the Group I-like PC-binding myeloma proteins (PCBMP); the Group II sequences are closely related to V kappa 1-3. Isoelectric focusing analysis was also performed on the L chain of PCG1-1, as well as on L chains from PCBHP typical of Group I antibodies, and from an atypical PCBHP differing from Groups I and II in fine specificity. A Group I PCBHP and the atypical PCBHP expressed L chains related to V kappa 8 and V kappa 24, respectively. The L chains of another Group I PCBHP and of the Group II protein, PCG1-1, appeared different from those found in the PCBMP and from each other. The results indicate a more diverse expression of L chains in the memory anti-PC response than is represented by the PCBMP; both V kappa 8- and V kappa 24-derived L chains (and, presumably, somatic variants), as well as products of additional V kappa genes (V kappa 1-3), appear to be present in the anti-PC memory pool.

Amino Acid Sequence↗
PubMed1983

Genes of the major histocompatibility complex in mouse and man.

The genes of the major histocompatibility complex code for cell-surface molecules that play an important role in the generation of the immune response. These genes and molecules have been studied intensively over the last five decades by geneticists, biochemists, and immunologists, but only recently has the isolation of the genes by molecular biologists facilitated their precise characterization. Many surprising findings have been made concerning their structure, multiplicity, organization, function, and evolution.

Animals↗
PubMed1983

Nucleotide sequence of a light chain gene of the mouse I-A subregion: A beta d.

Ia (I region-associated) antigens are cell-surface glycoproteins involved in the regulation of immune responsiveness. They are composed of one heavy (alpha) and one light (beta) polypeptide chain. We have sequenced the gene encoding the A beta d chain of the BALB/c mouse. The presence of six exons is predicted by comparison with the complementary DNA sequences of human beta chains and with partial protein sequence data for the A beta d polypeptide. Sequence comparisons have been made to other proteins involved in immune responses and the consequent implications for the evolutionary relationships of these genes are discussed.

Animals↗
PubMed1983

Three T cell hybridomas do not contain detectable heavy chain variable gene transcripts.

We attempted to determine whether T cells express any VH gene segments. cDNA libraries were constructed from one suppressor and two helper T cell hybridomas. Both the library construction and screening were designed to maximize detection of a wide range of VH gene segments. One screening method should detect about half of the sequenced VH genes, while the second should detect most of these genes. The probability of detecting a VH gene homologous to the probes and present at 10 copies per cell was 77% for one helper cell cDNA library, 88% for the second helper cell library, and greater than 99% for the suppressor cell library. No cDNA clones with VH gene segments were detected. From this result, we conclude that VH gene segments are not likely to encode the antigen-specific receptor in the cells we tested.

Animals↗
PubMed1983

Use of DNA-mediated gene transfer to analyze the role of H-2Ld in controlling the specificity of anti-vesicular stomatitis virus cytotoxic T cells.

Mouse thymidine kinase (tk-) C3H L (H-2k) cells transformed by the technique of DNA-mediated gene transfer with the herpes simplex virus tk gene together with the BALB/c H-2Ld gene express H-2Ld molecules indistinguishable from their counterparts on spleen cells. An established cloned cell line (8-5) was used to assess the function of the H-2Ld antigen in determining the specificity of alloreactive as well as anti-vesicular stomatitis virus (VSV) cytotoxic T cells (CTL). Both anti-H-2d and anti-H-2Ld CTL displayed a cytotoxic effect against 8-5 cells but not a control cell line transformed with the tk gene only (tk+ cells). Further evidence that 8-5 cells express H-2Ld was provided by the finding that monoclonal anti-H-2Ld but not H-2Dd antibodies blocked target cell lysis by the effector cells. Both BALB/c (H-2d) and DBA/2 (H-2d) animals generated anti-VSV CTL that lysed infected 8-5 but not tk+ cells. To further establish that H-2Ld controlled the specificity of the effector cells, a monoclonal antibody directed against H-2Ld was shown to inhibit lysis of infected 8-5 target cells. To determine whether other H-2d-encoded gene products could serve as restricting antigens for anti-VSV CTL in BALB/c animals, unlabeled VSV infected 8-5 cells were tested for their ability to block lysis of 51chromium-labeled P815 (H-2d)-infected target cells. The 8-5-VSV inhibitor cells inhibited lysis to a slightly lesser extent than unlabeled P815-VSV cells, indicating that H-2Ld plays a major if not exclusive role in restricting anti-VSV CTL in H-2d animals.

Animals↗
PubMed1983

Expression of complete transplantation antigens by mammalian cells transformed with truncated class I genes.

Mouse L cells transformed with the cloned class I genes of the major histocompatibility complex of the mouse express transplantation antigens with serological determinants of the donor haplotype. However, transformation with the truncated subclones of a BALB/c H-2Ld gene containing the exons encoding the external domains also leads to the production of cells which express complete cell-surface molecules. Moreover, full-length products of the foreign haplotype, as judged by serological and biochemical criteria, are generated independently of the use of carrier DNA in transformation. However, the frequency of productive transformation is substantially less than that obtained with a complete gene. The most plausible explanation for these phenomena involves homologous recombination between host chromosomal and donor class I sequences.

Animals↗
PubMed1983

Combining site specificities of mouse hybridoma antibodies to dextran B1355S.

The combining sites of 12 mouse hybridoma antibodies to dextran B1355S have been characterized by quantitative precipitin assay. All antibodies preferentially bind the immunizing antigen B1355S and two other class I dextrans, B1498S and B1501S, but show substantial differences in the extents to which they cross react with class I dextrans, suggesting their clustering into five groups. Three myeloma proteins, CAL20 TEPC1035, J558, and MOPC104E, which bind dextran B1355S, each fall into a different group. There appears to be a substantial, but imperfect, correlation of DH region structure and individual idiotypic determinants with dextran binding patterns. Proteins with RY DH segments and IdI (J558) idiotypes are in groups 1 or 3, and proteins with YD DH segments and IdI (MOPC104E) idiotypes are exclusively in group 5. However, identical patterns of precipitin curves accompany very different sequences in CDR3. Antibodies of group 1, which react only with class II dextrans, differ the most in primary sequence, a finding suggesting that subsites responsible for cross reactivity with class I dextrans may be blocked and that this may be effected by side chains of different amino acids. This finding delineates a new aspect of the relationship of variability in amino acid sequence to antibody complementarity.

Amino Acid Sequence↗
PubMed1983

Expression and function of transplantation antigens with altered or deleted cytoplasmic domains.

Two mutants of the class I gene encoding the H-2Ld transplantation antigen have been constructed. In one mutant the cytoplasmic domain of the class I molecule has been altered by deletion of 24 of the 31 C-terminal residues, and in the second the C-terminal 25 residues of the cytoplasmic domain have been replaced with a unique sequence of 19 amino acids. These mutant class I genes have been transferred into mouse L cells by DNA-mediated gene transfer. Both mutant genes are expressed at normal levels on the cell surface, and they have charge properties and sizes consistent with the introduced alterations. These mutant Ld molecules can serve as target antigens for allogeneic cytotoxic T cells and as restricting elements for virus-specific cytotoxic T cells. These results show that the 24 residues replaced or deleted from the carboxy terminus of the class I molecule are not required for its transport to or integration in the plasma membrane, nor for its function as a target antigen or a restricting element during T-cell-mediated cytotoxicity.

Amino Acid Sequence↗
PubMed1983

Genetic mapping in the major histocompatibility complex by restriction enzyme site polymorphisms: most mouse class I genes map to the Tla complex.

From a genomic library constructed from sperm DNA of the inbred BALB/c mouse, we previously isolated 54 cosmid clones that contain 36 class I genes and can be divided by restriction map analyses into 13 gene clusters. We have isolated single- and low-copy DNA probes from each of these clusters to visualize restriction enzyme site polymorphisms in the DNAs from various congeneic and recombinant congeneic mice. These polymorphisms permit us to map each of the 13 cosmid clusters to a precise location in the major histocompatibility complex of the mouse. Thirty-one of 36 class I genes map into the Tla complex of the major histocompatibility complex whereas the remaining 5 genes map to the H-2 complex. Thus, all 36 class I genes are located in the major histocompatibility complex. Analysis of the number of restriction enzyme fragments visualized by the single- and low-copy DNA probes suggests that the class I genes in different inbred strains of mice probably undergo gene duplications and deletions, presumably by homologous but unequal crossing-over.

Animals↗
PubMed1983

RNA transcripts for I-J polypeptides are apparently not encoded between the I-A and I-E subregions of the murine major histocompatibility complex.

The I-J subregion of the mouse major histocompatibility complex has been reported to encode antigenic determinants expressed by suppressor T cells. Previously, cosmid clones were obtained from mouse sperm DNA that contain all of the sequences between the I-A and I-E subregions, where I-J has been mapped genetically. However, hybridization of these sequences to RNA prepared from several I-J-positive suppressor T-cell hybridomas did not reveal the presence of a transcript. In addition, no rearrangements in this DNA were detected in the suppressor T cells that we have analyzed. Our results indicate that the I-J polypeptides are not encoded between the I-A and I-E subregions of the major histocompatibility complex. We discuss several hypotheses concerning the possible location and expression of I-J genes.

Animals↗
PubMed1982

Mouse c-myc oncogene is located on chromosome 15 and translocated to chromosome 12 in plasmacytomas.

Hybridization studies with viral oncogene probes indicate that c-myc, the cellular gene homologous to the transforming gene of avian myelocytomatosis virus, resides on mouse chromosome 15 and in many plasmacytomas is translocated to the antibody heavy chain gene locus on chromosome 12. The transcriptional orientation of the translocated c-myc sequence is opposite the orientation of the adjacent C alpha gene that codes for the heavy chain of immunoglobulin A. The translocated c-myc sequence is not the same oncogene detected in urine plasmacytomas by the NIH-3T3 cell transformation assay.

Animals↗
PubMed1982

DNA sequence of the gene encoding the E alpha Ia polypeptide of the BALB/c mouse.

A 3.4-kilobase DNA fragment containing the gene coding for the E alpha chain of an Ia (I region-associated) antigen from the BALB/c mouse has been sequenced. It contains at least three exons, which correlate with the major structural domains of the E alpha chain-the two external domains alpha 1 and alpha 2, and the transmembrane-cytoplasmic domain. The coding sequence of the mouse E alpha gene shows striking homology to its counterpart at the DNA and protein levels. The translated alpha 2 exon demonstrates significant similarity to beta 2-microglobulin, to immunoglobulin constant region domains, and to certain domains of transplantation antigens. These observations and those of others suggest that the Ia antigen, transplantation antigen, and immunoglobulin gene families share a common ancestor.

Animals↗