N. Ghanem

New subgroups in the human T cell rearranging V gamma gene locus.

Two new V gamma genes in humans are described from rearrangement in T cell lines, which constitute single members of new V gene subgroups of the T‐cell rearranging gamma (TRG gamma) locus. These two genes (herein designated as belonging to V gamma III and V gamma IV subgroups) are located between V gamma I/V gamma II subgroups and the constant (C) gamma genes. The existence of these new genes brings the number of different, potentially useable, human TRG V gamma genes to eight (excluding at least five pseudo V gamma genes) and the number of distinct subgroups to four. Polymorphism in the sequence of the V gamma II subgroup gene is also described and rearranged fragment sizes which make possible an unequivocal assignment of a V gamma rearrangement are given. These results extend previous conclusions of the inherited diversity of the human TRG V gamma locus.

No detectable malignant B cells in the peripheral blood of patients with multiple myeloma.

Summary Previous studies have reported the presence of idiotypic B lymphocytes in the blood of patients with multiple myeloma (MM), suggesting that they may belong to the malignant clone. This led us to investigate by southern blot analyses the pesence of tumour‐specific immunoglobulin‐gene (Ig‐gene) rearrangements in the peripheral‐blood mononuclear cells of 21 MM patients. This method was shown to detect clonal cells when they represent as little as 2% of the cell population. B‐cell‐enriched fractions were also studied in nine cases. An occasional contamination by cruclatin malignant plasma cells was carefully evaluated using immunofluorescence. Clonal rearrangements were observed in only two cases, in which a contamination by myeloma cells was evident. In these cases the use of different endonucleases clearly demonstrated that these Igclonal rearrangements involved post‐switched cells. No clonal rearrangement was found when contamination by myeloma cells was absent. Our results demonstrate the absence of detectable B cells involved in the myeloma clone in the peripheral blood of patients with MM.

Exon duplication and triplication in the human T-cell receptor gamma constant region genes and RFLP in french, lebanese, tunisian, and black african populations

The human T-cell receptor gamma (TCRG) locus comprises 14 variable genes (TRGV), five joining segments (TRGJ), and two constant region genes (TRGC). The constant gamma 1 gene, TRGC1, consists of three exons, whereas the TRGC2 gene contains four or five exons due to the duplication or triplication of exon 2 and spans 9.5 kb or 12 kb, respectively. In this paper, we define the alleles of the T-cell receptor gamma J2 and C2 genes, and we show that two Hind III allelic fragments, 5.4 kb and 8 kb, characterize unambiguously the C2 gene with duplication or triplication of exon 2. We show also that the cDNA of the HPB-MLT cell line results from the transcription of an allelic TRGC2 gene with duplicated exon 2. We propose a model involving unequal crossing-overs to explain the organization and the evolution of the TRGC locus. Moreover, we analyze the TCRG haplotypes in four different populations (French, Lebanese, Tunisian, and Black African) to underline their interest for population genetics.

A gamma 3 hinge region probe: first specific human immunoglobulin subclass probe

We report the first specific human immunoglobulin subclass probe which was obtained by subcloning the gamma 3 hinge region. This specific γ3 probe allowed us to identify with certainty the Cγ3 gene on Southern genomic blots to describe the first Cγ3 restriction fragment length polymorphism (EZZ γ3 RF) and to show that an IgG3 selective deficiency previously described serologically was not due to a deletion of the C3 gene. Such a probe should be particularly useful for screening libraries from individuals with IgG3 immunodeficiencies or presenting unusual Cγ3 genes and consequently for studying the Cγ gene evolution. Immunoglobulin IgCH gene (Human) Gm allotype Restriction fragment length polymorphism Immunoglobulin G3 deficiency Hinge

Polymorphism of MHC class III genes: definition of restriction fragment linkage groups and evidence for frequent deletions and duplications.

SummaryThe loci for the complement proteins BF and C2 and the two loci for C4 are closely linked to one another, as are the duplicated steroid 21 hydroxylase (21-OHase) genes to the C4A and C4B loci. The alleles of these four loci occur in specific combinations termed “complotypes”. We have studied the gene frequencies of their different products in the Lebanese population and compared these values with those found in other populations. We observed a novel complotype (S B 4 6) in one family and a complotype with a so far undescribed variant of the C4A locus. Using several restriction fragment length polymorphisms (RFLPs), we have defined restriction fragment linkage groups. The combined use of C4 and 21-OHase probes allowed us to detect different types of deletions and duplications at these loci in the Lebanese population.

Deletion, insertion, and restriction site polymorphism of the T-cell receptor gamma variable locus in French, Lebanese, Tunisian, and black African populations.

The human T-cell receptor gamma region spans 160 kb of genomic DNA and is densely populated by coding sequences. Restriction fragment length polymorphisms have been previously documented for the constant region genes, the joining segments, and the variable genes belonging to subgroups I and IV. Here were further define the polymorphism of theV gamma I subgroup genes, based on complete mapping of theEco RI andTaq I allelic restriction fragments. We describe seven haplotypes; five result from polymorphic restriction sites, the sixth corresponds to a deletion of about 10 kb encompassingV4 andV5, and the seventh results from an insertion of an additional gene,V3P, betweenV3 andV4. As a consequence of the deletion or insertion polymorphism, the number ofV gamma I subgroup genes vary from seven in haplotypeTRGVI*3 to ten in haplotypeTRGVI*4, whereas the most common haplotype,TRGVI*1, has nineV genes, five of them being functional. Frequencies of the differentTRGVI haplotypes in French, Lebanese, Tunisian, and Black African populations are given.

BamHI and SacI RFLPs of the human immunoglobulin IGHG genes with reference to the Gm polymorphism in African people

SummaryIn this paper, we extend the study of the IGHG gene RFLPs in black African persons and in some other individuals characterized by a Negroid admixture. We demonstrate a polymorphism that is much more important in black Africans, that in Caucasoids, mainly for the IGHG3 and G1 genes, the most 5′ members of the IGHG multigene family. These genes encode for the IgG3 and IgG1 subclasses, which are of crucial biological importance.