Experimental and clinical immunogenetics最新文献

Deoxyribonuclease I (DNase I) was purified from Xenopus laevis pancreas to apparent electrophoretic homogeneity using a series of column chromatographies. The purified enzyme showed a molecular mass of about 36 kDa and maximum activity at pH 7.0-8.0, required divalent cations, Ca2+ and Mg2+, for its activity, and was inhibited by EDTA, EGTA and an antibody specific to the enzyme, but not by G-actin. The N-terminal amino acid sequence of the enzyme up to the 37th residue shared 38-44% homology with that of mammalian DNases I derived from bovine, ovine, porcine, rat, mouse, rabbit and human. A systematic survey of DNase I activity distribution in 20 different kinds of frog tissues showed that the pancreas and rectum produced higher amounts than other tissues. This is the first report concerning the purification and chemical and immunological characterization of frog pancreatic DNase I.

The production of antibodies against nonnominal immunoglobulin allotypes in rheumatoid arthritis (RA) patients suggests that the immune system of these patients has been exposed to such foreign allotypes. The presence of nonnominal allotypes is, however, a genetic enigma. We searched for nucleotide sequences specific for nonnominal G3mg and G3mb copies in individuals homozygous for these alleles. Using a sensitive and specific nested polymerase chain reaction (PCR) method with genomic DNA from blood of 18 RA patients and 5 normal controls, we found G3mg sequences in 18 of 18 tested G3mb homozygous persons. The allele specificity of the PCR fragments was confirmed by sequencing and RFLP analysis. The PCR products contained genomic nonspliced parts of the nonnominal sequences. An analysis of cDNA from inflammatory tissue of 5 RA patients detected nonnominal G3mb sequences in 1 of 3 tested G3mg homozygotes and G3mg sequences in 2 of 2 tested G3mb homozygotes. The cDNA-derived PCR products contained sequences from normally spliced nonnominal Ig fragments. The results also showed that the nonnominal Ig sequences were present in very low copy numbers, lower than the Mendelian 1-2 copies per cell. The origin of such a low copy number of Ig gene fragments may be explained by a virus-mediated capture and transfer mechanism of Ig gene fragments generated by the normal Ig switch-associated gene excision process.

The BAT1 gene (D6S81E) encodes a member of the DEAD-box family of RNA-binding proteins, and lies in the central MHC. This region contains genes which affect susceptibility to immunopathological diseases. A 14-kb section of the human MHC containing the BAT1 gene and a further 5-kb telomeric of BAT1 was sequenced using DNA from individuals homozygous for HLA-A1, B8, DR3 and HLA- A1, B57, DR7. Analysis of our sequences and the previously reported human cDNA sequence showed that the expressed sequence of the 8.1 and 57.1 haplotypes is identical with only minor substitutions in the introns. Phylogenetic analysis suggests BAT1 may be a translation initiation factor. Screening of cells and tissues for BAT1 mRNA suggests an abundant member of a family of proteins expressed in multiple cell types, notably macrophages and hepatocytes. Expression was independent of MHC haplotype, consistent with the lack of sequence polymorphism.

'Protein displays of the Human Immunoglobulin Heavy, Kappa and Lambda Variable and Joining Regions', the 6th report of the 'IMGT Locus on Focus' section, comprises 4 figures: (1) 'Protein display of human IGH V-REGIONs'; (2) 'Protein display of human IGK V-REGIONs'; (3) 'Protein display of human IGL V-REGIONs and V-PREB REGION'; (4) 'Protein display of human IGH, IGK and IGL J-REGIONs', and 1 table entitled: 'FR-IMGT and CDR-IMGT length of the human IGHV, IGKV, IGLV and V-PREB genes'. These figures and table are available at the IMGT Marie-Paule page from IMGT, the international ImMunoGeneTics database (http://imgt.cnusc.fr: 8104) created by Marie-Paule Lefranc, Université Montpellier II, CNRS, France.

Sera from patients with rheumatoid arthritis (RA) were from the very start instrumental in detecting and delineating the human immunoglobulin (Ig) allotypes in the Gm system. Knowledge that human Ig production is under Mendelian control and not determined by templates of antigen would not have come to the fore if it were not for RA patients. Worldwide experience shows that RA patients are prone to mount an immune response to human Ig allotypes. Major Gm allotypes are defined at the amino acid and nucleotide levels. Gene technology has been developed for defining these allotypes. Studies of the Gm allotypes and anti-Gms have led to two apparently paradoxical findings: (1) In conflict with Mendelian law, non-nominal or hidden allotypes have been observed and recently documented at the DNA level. (2) In RA, an immune response to other individuals' Mendelian allotypes is prevalent, although RA is generally considered an autoimmune disease. These findings led us to conclude that RA is not initially an autoimmune disease but a gene transfer disease. A brief review of viral high-jacking and transfer of human genes is given along with reasons for considering the herpesvirus family in particular. Genes determining incompatible Ig allotypes are transferred. We have shown that these genes are expressed in RA synovia. Ig-anti-Ig complexes arise and may have arthritogenic potential, as observed in serum sickness.