T-Cell γ Gene is Allelically but not Isotypically Excluded and is not Required in Known Functional T-Cell Subsets

The T-cell γ genes, structurally related to immunoglobulin genes and the T-cell antigen-receptor α - and β -chain genes, undergo somatic rearrangement in T-lineage cells. However, the role of the T-cell γ genes has not yet been determined. To determine the potential for γ gene expression in a set of well-characterized, cloned T-cell lines, we cloned all of the rearranged γ genes from each cell line. The genes were sequenced to determine if the junction of the variable and joining regions maintained the proper translational reading frame. We then attempted to correlate the presence of an in-frame γ gene with a T-cell subset. We were unable to establish such a correlation. We found evidence, however, that allelic exclusion influences the rearrangement of the γ gene. This is consistent with the idea that the γ gene product participates in establishing a clonally diverse population of T cells recognizing a polymorphic ligand. Isotypic exclusion does not apply to the γ gene, however, suggesting different roles for the different γ gene isotypes.