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C T Lutz

Publications and source records attributed to C T Lutz.

At least 37 records · Page 2Linked to original sources
PubMed1995

Low HLA-C expression at cell surfaces correlates with increased turnover of heavy chain mRNA.

In comparison with HLA-A and -B, the protein products of the HLA-C locus are poorly characterized, in part because of their low level of expression at the cell surface. Here, we examine how protein-protein interactions during assembly and regulation of the mRNA level affect cell surface expression of HLA-C. We find that intrinsic properties of the HLA-C heavy chain proteins do not correlate with low cell surface expression: HLA-C heavy chains associate and dissociate with beta 2-microglobulin (beta 2m) at rates comparable to those found for HLA-A and -B, and increased competition for beta 2m does not alter the surface expression of HLA-C. From studies of chimeric genes spliced from the HLA-B7 and -Cw3 genes, we find that chimeric proteins containing the B7 peptide-binding groove can have low cell surface expression, suggesting that inefficiency in binding peptides is not the cause of low cell surface expression for HLA-C. The surface levels of HLA-A, -B, or -C in cells transfected with cDNA can be similar, implicating noncoding regions of HLA-C heavy chain genes in the regulation of surface expression. We find that HLA-C mRNA is expressed at lower levels than HLA-B mRNA and that this difference results from faster degradation of the HLA-C message. Experiments examining chimeric B7/Cw3 and B7/Cw6 genes suggest that a region determining low expression of HLA-C is to be found between the 3' end of exon 3 and a site in the 3' untranslated region, approximately 600 bases downstream of the translation stop codon.

Base Sequence↗
PubMed1995

NK cell recognition of MHC class I. NK cells are sensitive to peptide-binding groove and surface alpha-helical mutations that affect T cells.

NK cells directly or indirectly recognize MHC class I molecules, but the exact structures recognized remain poorly defined. We address the hypothesis that NK cells, like T cells, directly contact peptide/MHC class I complexes. This hypothesis predicts that NK-mediated killing is inhibited by amino acid substitutions in the MHC class I peptide-binding groove and in solvent-accessible alpha-helical residues proposed to contact the TCR. In our model system, target cell HLA-B*0702 inhibited killing by unstimulated peripheral blood NK cells. NK-mediated killing was increased significantly by 6 of 11 peptide-binding groove mutations and 6 of 12 TCR contact site mutations, but only 1 of 6 mutations outside these sites. Many of the mutations that inhibited NK-mediated killing prohibited killing by 12 alloreactive CTL clones. These data suggest that NK receptors directly contact HLA-B*0702, focusing on the peptide-binding groove and surrounding alpha-helices. NK cell lines exhibited multiple HLA recognition patterns, which is consistent with nonuniform expression of MHC receptors by NK cells. We propose that NK cells, like alpha beta T cells and some anti-MHC Abs, directly or indirectly recognize MHC-bound peptides.

Binding Sites↗
PubMed1994

Bw4-reactive and Bw6-reactive antibodies recognize multiple distinct HLA structures that partially overlap in the alpha-1 helix.

Bw4 and BW6 epitopes are expressed by mutually exclusive sets of HLA-B alleles and some HLA-A and HLA-C alleles. To test whether antithetical structures are required to express Bw4 and Bw6 epitopes, we measured binding of Bw4-reactive and Bw6-reactive alloantibodies and mAbs to HLA-B7 variants. A triple substitution of HLA-B7 alpha-1 helix residues 80, 82, and 83 created Bw4 and destroyed Bw6 epitopes detected by alloantibodies and mAbs. Both Bw4-reactive and Bw6-reactive mAbs competed for binding to HLA-B7 variants with single substitutions at residues 82 and 83. Substitutions of residues H93 and D119 which form a salt bridge in HLA-A2 also permitted binding by both Bw4-reactive and Bw6-reactive mAbs, suggesting that Bw4 and Bw6 epitopes are conformationally dependent. Six Bw4-reactive mAbs showed four distinct patterns of binding to HLA-B7 variants. Detailed analysis of 74 HLA-B7 single-residue variants showed that Bw6-reactive SFR8-B6 binding was prohibited by mutations altering the distal end of the alpha-1 helix and the nearby connecting loop. In contrast, Bw6-reactive BB7.6 binding required both alpha-1 and alpha-2 helix residues. Thus, Bw4-reactive and Bw6-reactive Abs recognize multiple distinct HLA structures that partially overlap in the alpha-1 helix. As both Bw4 and Bw6 epitopes are expressed by some HLA-B7 variants, mutually exclusive expression of Bw4 and Bw6 epitopes in naturally occurring HLA class 1 molecules may reflect evolutionary pressure.

Antibodies, Monoclonal↗
PubMed1994

Presence of Epstein-Barr virus in many types of benign and malignant lymphoid lesions. Detection by polymerase chain reaction and in situ hybridization.

Epstein-Barr virus (EBV) has been detected in African Burkitt's lymphoma, posttransplant lymphoproliferative disease, and a variable fraction of Hodgkin's lymphomas. To assess if EBV is associated with other lymphoid proliferations, we evaluated a wide variety of benign and malignant lymphoid lesions, using polymerase chain reaction and a sensitive in situ hybridization method. Abundant EBV+ cells were seen in posttransplant lymphomas, some B cell immunoblastic lymphomas, and in tonsils from patients with infectious mononucleosis. Intermediate numbers of EBV+ cells were seen in a mixed B cell lymphoma, peripheral T cell lymphomas, and in syncytial variants of Hodgkin's disease as well as a lymph node from a patient with infectious mononucleosis. Low numbers of EBV+ cells were detected in normal and reactive lymph nodes, B and T cell lymphomas, and Hodgkin's lymphomas. The variable extent of EBV infection in lymphoid lesions suggests that EBV may play a variety of roles in the development of malignant and nonmalignant lymphoid lesions.

Base Sequence↗
PubMed1993

HLA-B*0702 antibody epitopes are affected indirectly by distant antigen residues.

We examine the effect of mutations in the HLA-B*0702 alpha 1 domain on the binding of several well-characterized monoclonal antibodies. BB7.1 recognizes the alpha-helix, with a special requirement for residue 67. Combined with an established requirement for the alpha 2 alpha-helix, BB7.1 appears to span the B*0702 peptide-binding groove. Alternatively, BB7.1 epitope conformation may be altered by distant B*0702 sites. ME1 and B27M1 recognize connecting loop residues 41 and 43 and alpha 1 alpha-helical residues 67-71. Instead of contacting residue 67-71 side chains directly, however, ME1 appears to recognizes a B*0702 configuration that depends upon the proper interaction of these and other HLA residues. In addition to solvent-accessible residues 41 and 43, the B27M1 epitope depends on solvent-inaccessible residue 32 at the bottom of the peptide-binding groove. MB40.2, known to require residues 169-182 near the alpha 2-alpha 3 junction, also requires the proper combination of distant residues in the alpha 1 beta-strand and alpha-helix. The effect of mutations near the peptide-binding groove suggests that bound peptides may directly or indirectly affect HLA epitopes. These results illustrate that HLA epitope conformation is very sensitive to changes at distant HLA sites and forecast that epitope models based on sequential amino acid residues will often fail to predict HLA epitopes.

Animals↗
PubMed1993

Epitope fine specificity of human anti-HLA-A2 antibodies. Identification of four epitopes including a haptenlike epitope on HLA-A2 at lysine 127.

Anti-HLA-A2 CREG antibodies were purified from seven individuals by affinity chromatography. The binding of the purified antibodies to single or multiple amino acid variants of HLA-A2.1 was measured with an inhibition RIA. Substitutions at 10 amino acid residues in the polymorphic alpha 1 and alpha 2 domains were important for human antibody binding; eight of these have previously been shown to be important in the binding of murine anti-HLA-A2 CREG antibodies. Unlike any previously reported murine mAbs, the binding of antibodies from two individuals was eliminated by a substitution at the HLA-A2, -24, -28 shared loop amino acid residue lysine 127. Conversely, when the asparagine at residue 127 on the non-cross-reactive HLA-A3 was replaced with lysine, antibody binding was completely restored. The results further suggest that both lambda- and kappa-containing human antibodies that bind to this region may recognize lysine 127 as a haptenlike epitope. Anti-HLA-A2 antibodies that recognized a conformational epitope defined by changes at glycine 62 in the alpha 1 domain were predominated by lambda light chains whereas those that recognize an epitope defined by a loop residue at tryptophan 107 in the alpha 2 domain were predominated by kappa light chains. The data are consistent with a model of restricted epitope recognition of HLA-A2 by human B cells that is similar to, but distinct from, epitope recognition by mouse B-cell hybridomas, and may help to explain the phenomenon of public or cross-reactive idiotypes in the HLA system.

Animals↗
PubMed1992

Epstein-Barr virus integration in human lymphomas and lymphoid cell lines.

BACKGROUND: Epstein-Barr virus (EBV) is maintained as an episome in most infected cells. The presence of fused terminal restriction enzyme fragments distinguishes the circular DNA form from the linear virion form. METHODS: EBV genomic structure was analyzed in 8 lymphoid cell lines and 21 human lymphoma specimens by the Southern blot technique. RESULTS: Evidence of viral integration into host chromosomal DNA was identified in four cell lines. In the Namalwa and BL30-B95.8 cell lines, integration occurred through the terminal repeat (TR) sequences. In the BL41-P3HR1 and BL41-B95.8 cell lines, there was loss of left-end viral genomic sequences, including ori-P sequences required for episome maintenance, implying that integration was required for viral genome persistence. Integration was not detected in four other cell lines (Raji, Daudi, B95.8, and BL30-P3HR1). In 21 EBV-containing human lymphomas, including 18 immunodeficiency-related lymphomas, fused TR sequences were identified without evidence of viral genomic integration. CONCLUSIONS: These findings suggest that, although viral integration is common in Burkitt lymphoma cell lines infected in vitro, integration is not common in human lymphomas that develop in vivo in normal or immunodeficient people.

Adolescent↗
PubMed1992

Mutagenesis around residue 176 on HLA-B*0702 characterizes multiple distinct epitopes for anti-HLA antibodies.

Preformed antibodies against HLA-A,B,C molecules cause hyperacute rejection of transplanted allogeneic tissues. To understand better the molecular basis of hyperacute rejection, narrowly reactive anti-HLA-B*0702 monoclonal antibodies have been studied. Previous epitope mapping studies of these monoclonal antibodies by mutating B*0702 have conflicted with antibody-blocking studies. To resolve these discrepancies, we mutated B*0702 residues around the antigenically important residue 176, and measured anti-B*0702 antibody binding. Antibody MB40.2 binding is abrogated by mutations at residues 169, 180, and 182, close to residue 176 in the primary structure. However, MB40.2 binding is not affected by 12 other B*0702 mutations close to residue 176 in the tertiary structure. This suggests that MB40.2 may recognize a sequential B*0702 epitope including residues between positions 169-182. Antibody BB7.1 binding requires B*0702 alpha 2-domain residues 166 and 169. Competition for B*0702 residue 169 explains why MB40.2 and BB7.1 crossblock. Because BB7.1 binding also requires B*0702 alpha 1-domain residues, BB7.1 may contact both alpha-helices, straddling the B*0702 peptide-binding groove. Previous results showed that both MB40.2 and MB40.3 binding require B*0702 residues 176/178. However, MB40.3 binding is not affected by any of 15 other mutations near residue 176. This suggests that MB40.3 does not contact residues 176/178; rather, residues 176/178 appear to affect MB40.3 binding by subtly influencing B*0702 conformation. Thus, monoclonal antibodies influenced by a defined B*0702 region around residue 176 appear to recognize three different types of epitopes. This suggests that human alloantibodies also recognize diverse types of HLA epitopes.

Antibodies, Monoclonal↗
PubMed1991

Clonal immunoglobulin gene rearrangement in the infarcted lymph node syndrome.

The authors report a case of complete lymph node infarction in which a specific etiology could not be determined by morphologic or immunophenotypic studies; however, clonal rearrangement of the immunoglobulin gene was demonstrated by Southern blot hybridization of DNA extracted from the necrotic tissue. A subsequent lymph node biopsy later was diagnosed as malignant lymphoma, using morphologic, immunophenotypic and genotypic criteria. Identical clonally rearranged bands were present in DNA from both the infarcted nodal and the subsequent tissue biopsies. In the setting of lymph node necrosis, gene rearrangement studies may provide diagnostic information concerning clonality, even if morphologic and immunophenotypic studies are indeterminate for a lymphoproliferative process.

Aged↗
PubMed1991

Establishment of a reference interval for beta 2-microglobulin in cerebrospinal fluid with use of two commercial assays.

Increased concentrations of beta 2-microglobulin in cerebrospinal fluid have been used to detect central nervous system involvement with metastatic cancer and with neurological complications of AIDS. However, no adequate reference interval study has been reported for beta 2-microglobulin in cerebrospinal fluid. We established a reference interval with both the Abbott IMx microparticle enzyme-linked immunoassay (EIA) (0.6-2.0 mg/L) and the Pharmacia beta 2-micro EIA 96 method (0.8-2.2 mg/L) for beta 2-microglobulin in cerebrospinal fluid. The two methods correlate well, with the latter method giving slightly higher values. beta 2-Microglobulin increases with age in adults by about 0.1 mg/L every 7.5 years, with no significant difference between genders.

Adult↗
PubMed1990

Kappa immunoglobulin light chain gene rearrangement in a T-lineage chronic lymphocytic leukemia.

Until recently, only B-lineage lymphoid cells were observed to rearrange kappa immunoglobulin light chain genes. The authors examine peripheral blood mononuclear cells from a patient with chronic lymphocytic leukemia. More than 90% of these cells bound T-lymphocyte specific antibodies, failed to bind B-lymphocyte specific antibodies, had rearranged T-cell receptor beta-chain genes and had retained immunoglobulin heavy chain genes in the germline configuration. Despite these T-lineage markers, the majority of these cells had rearranged kappa immunoglobulin light chain genes. This provides the first conclusive evidence for rearranged kappa genes in malignant T-lineage cells and warns that gene rearrangement studies alone cannot indicate tumor cell lineage. To detect T-lineage cells that rearrange immunoglobulin genes, multiple immunophenotypic and genotypic parameters must be evaluated. These cells may provide important models to study how normal and malignant cells rearrange lymphocyte receptor genes.

Adult↗
PubMed1990

The diagnostic utility of immunophenotyping and immunogenotyping in the pathologic evaluation of lymphoid proliferations.

One hundred eighty-two specimens of suspected lymphoma and lymphocytic leukemia were examined by morphology, immunophenotype, and immunogenotype (genotype) in order to answer the following questions: How often and in what situations does immunophenotyping help resolve a diagnostic problem that is not resolved by morphology? How frequently does genotyping help resolve a diagnostic problem that is not resolved by morphology and immunophenotyping? Of 182 cases for which fresh tissue was available, sixty-five cases were considered morphological diagnostic problems: There were 32 cases of neoplasia versus non-neoplastic proliferation, 16 cases of neoplasia with undifferentiated or ambiguous morphology, and 17 cases of lymphoma or lymphocytic leukemia with an uncertain subtype. Immunophenotyping helped to resolve 33 of these 65 cases. Of the remaining 32 cases genotyping helped to resolve the diagnosis in 16. These results suggest that immunophenotyping may diagnose approximately 50% of those cases which present a morphological problem, and that genotyping is also helpful in a limited but significant number of problem cases.

Diagnosis, Differential↗
PubMed1988

Genetics and primary structure of V kappa gene segments encoding antibody to streptococcal group A carbohydrate. Comparison of V kappa gene structure with idiotope expression.

Two gene segments, V kappa-25-39 and V kappa-25-47, that encode antibody to streptococcal group A carbohydrate in A/J mice were found to be more than 95% homologous in nucleotide sequence in both coding and noncoding regions. It was previously shown that V kappa-25-39 encodes immunoglobulins that express the IdX and IdI-1 idiotopes, whereas V kappa-25-47 encodes IdX+, and IdI-1- immunoglobulins. V kappa gene segments that were clearly allelic to V kappa-25-47 are used to encode IdX+, IdI-1- anti-group A carbohydrate antibodies by C.B20 mice and likely by C57BL/6 mice. Murine strains that are deficient in IdI-1 idiotope expression were investigated by Southern blotting with a 5' probe from V kappa-25-39. Two IdI-1-deficient strains, CE/J and C58/J, had a grossly altered V kappa gene segment structure compared with the A/J prototype. In contrast, the IdI-1-deficient strain, C57BL/6, was indistinguishable from A/J with the 5'V kappa-25-39 probe, indicating that more subtle genetic changes account for the loss of IdI-1 expression in C57BL/6 mice. The evolution of V kappa-25-39 and V kappa-25-47 gene segments was deduced by comparison with the homologous V kappa 24B gene segment of Mus pahari. V kappa-25-39 and V kappa-25-47 likely have recently duplicated once in A/J and related strains of laboratory mice and may have duplicated again in CE/J mice. Thus, individual members of the V kappa 24 gene family, to which V kappa-25-39 and V kappa-25-47 belong, are preserved while the number of gene copies expands or contracts. This fact is strong evidence that evolutionary forces have maintained the V kappa 24 gene family, all of which encode antibody specific for carbohydrate found in bacterial pathogens.

Amino Acid Sequence↗
PubMed1987

Molecular dissection of the murine antibody response to streptococcal group A carbohydrate.

Monoclonal antibodies (mAb) to streptococcal group A carbohydrate (GAC) are encoded by a minimum of two VH, four JH, four V kappa, three J kappa, one V lambda, and one J lambda gene segments. The IdX, IdI-1, and Id5 idiotypic determinants are expressed by anti-GAC mAb and are found on free kappa chains. Each pattern of these determinants is encoded by a distinct V kappa gene segment, apparently without the requirement for a particular J kappa, VH, or JH gene segment, or somatic mutation. In contrast, the binding site-associated idiotypic determinant IdI-3a does not correlate with any single V or J gene segment.

Animals↗
PubMed1987

Syrinx 2A: an improved lambda phage vector designed for screening DNA libraries by recombination in vivo.

The Syrinx 2A phage and pi AN13 plasmid were designed for screening of DNA libraries by homologous recombination in vivo. Syrinx 2A carries multiple cloning sites and a recently identified lambda gene, rap (recombination adept with plasmid), required for efficient phage-plasmid recombination. We describe a rapid, reliable, and technically easy method to screen Syrinx 2A libraries, expand the resulting phage-plasmid cointegrates, and subclone plasmid in as little as 2 days. Recombination screening allows one specific member of a closely related multigene family to be isolated selectively.

Bacteriophage lambda↗