V beta gene polymorphism and a major polyclonal T cell receptor idiotype

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• The T cell receptor (TcR) is crucial for adaptive immunity, with its variable beta (V beta) gene pool exhibiting significant polymorphism.
• The KJ16 T cell receptor (TcR) marker is found on approximately 20% of peripheral T cells, with its distribution varying between mouse strains.

Purpose of the Study:

• To investigate the genetic basis for the strain-specific distribution of the KJ16 TcR marker.
• To determine the role of specific V beta genes in the generation of the TcR repertoire.

Main Methods:

• Analysis of genetic polymorphism in the V beta gene pool.
• Detection of V beta gene expression using mRNA hybridization probes.
• Characterization of T cell hybrids and splenic T cells from different mouse strains.

Main Results:

• KJ16+ strains possess two homologous V beta genes absent in KJ16- strains.
• All tested functional KJ16+ T cell hybrids express a V beta gene from this subset.
• mRNA hybridization confirms the presence of these V beta genes in prototype KJ16+ splenic T cells.
• These two V beta genes can generate 20% of the TcR repertoire in cytotoxic and helper T cells.

Conclusions:

• Genetic polymorphism in V beta genes directly underlies the strain-specific presence of the KJ16 TcR marker.
• A small subset of V beta genes contributes significantly to the TcR repertoire diversity.
• Deletion of these specific V beta genes does not appear to impair overall T cell repertoire functionality.