Amino acid sequences of seven V beta, eight V alpha, and thirteen J alpha novel human TCR genes

T cell receptor alpha-chain and beta-chain junctional region homology in clonal CD3+, CD8+ T lymphocyte expansions in Felty's syndrome

OBJECTIVE

Up to 42% of patients with Felty's syndrome (FS) have peripheral blood expansions of CD3+,CD8+ large granular lymphocytes (LGLs). The aim of this study was to determine whether the T cell receptor (TCR) alpha- and beta-chain sequences of these expansions from different patients have features in common that would support the hypothesis of an antigen-driven process.

METHODS

Extraction of RNA from peripheral blood lymphocytes followed by synthesis of complementary DNA, inverse polymerase chain reaction (PCR) with TCR-specific primers, bacteriophage transformation, and sequencing of PCR products.

RESULTS

Structural analysis of TCR beta-chain usage in such patients demonstrated a junctional region motif comprising the amino acids -LG- or -RG- in 7 of 14 clonal sequences and the motif -GXG- in 8 of 14. A biased alpha-chain junctional region usage of a hydrophobic and/or basic amino acid at position 2 was seen in 5 of 8 expanded sequences. These features differed significantly from control sequences.

CONCLUSION

Given current models of TCR-peptide-major histocompatibility complex interaction, these observations are consistent with an antigen-driven, rather than a superantigen-driven, process in at least a subgroup of patients with FS.

Quantitative analysis of the usage of human T cell receptor alpha and beta chain variable regions by reverse dot blot hybridization

We previously developed an adaptor ligation-mediated PCR method to amplify the T cell receptor (TCR) cDNA pools. In the present study we applied reverse dot blot hybridization to PCR-amplified specimens for quantitative analysis of the usage of TCR alpha and beta chain variable (V) region. 44 VA sequence-specific oligonucleotide probes (SSOPs) and 38 VB SSOPs were synthesized corresponding to unique sequences of VA and VB subfamilies. Peripheral blood lymphocytes of ten healthy donors and five T cell clones established from bone marrow cells were examined for VA and VB usage using this method. The results were consistent with those obtained by a colony hybridization method and those by immunofluorescence staining using monoclonal antibodies to VA and VB. Thus, reverse dot blot hybridization for TCR V(alpha) and Vbeta is a new, easy and dependable technique useful for analysis of VA and VB usage by human T cells.

Gamma delta T cells are secondary participants in acute graft-versus-host reactions initiated by CD4+ alpha beta T cells

To examine the role of T cell subpopulations in an acute graft-versus-host (GVH) reaction, gamma delta T cells and alpha beta T cells expressing one of the two prototypic V beta families were negatively isolated from adult blood samples and injected into allogeneic chick embryos. CD4+ alpha beta T cells expressing either V beta 1 or V beta 2 receptors were equally capable of inducing acute GVH reactions, consistent with the idea that alpha beta T cell alloreactivity is determined by CDR3 variability. By themselves, the gamma delta T cells were incapable of inducing GVH reactions. However, host gamma delta T cells were recruited into the donor alpha beta T cell-initiated lesions, where they were activated and induced to proliferate. The data suggest that gamma delta T cells may play a secondary role in GVH reactions.

Human T-cell receptor variable gene segment families

Multiple DNA and protein sequence alignments have been constructed for the human T-cell receptor alpha/delta, beta, and gamma (TCRA/D, B, and G) variable (V) gene segments. The traditional classification into subfamilies was confirmed using a much larger pool of sequences. For each sequence, a name was derived which complies with the standard nomenclature. The traditional numbering of V gene segments in the order of their discovery was continued and changed when in conflict with names of other segments. By discriminating between alleles at the same locus versus genes from different loci, we were able to reduce the number of more than 150 different TCRBV sequences in the database to a repertoire of only 47 functional TCRBV gene segments. An extension of this analysis to the over 100 TCRAV sequences results in a predicted repertoire of 42 functional TCRAV gene segments. Our alignment revealed two residues that distinguish between the highly homologous V delta and V alpha, one at a site that in VH contacts the constant region, the other at the interface between immunoglobulin VH and VL. This site may be responsible for restricted pairing between certain V delta and V gamma chains. On the other hand, V beta and V gamma appear to be related by the fact that their CDR2 length is increased by four residues as compared with that of V alpha/delta peptides.