Human T cell receptor-gamma and -delta chain pairing analyzed by transfection of a T cell receptor-delta negative mutant cell line.

Specific TCR V gamma and V delta segments are found to be coordinately used on subpopulations of gamma delta T lymphocytes. The reasons for this phenomenon are unknown, but may include the inability of particular chains expressing unique V delta and V gamma segments to physically associate. V delta 2 is typically used together with V gamma 2 on human peripheral blood gamma delta T lymphocytes. To examine whether V delta 2 can be used in conjunction with distinct V gamma segments, a TCR- mutant of the human gamma delta T cell line MOLT-13, which expresses parental TCR gamma (V gamma 1.3) but not TCR-delta protein, was transfected with plasmids containing full-length TCR-delta cDNA using either V delta 2 or V delta 3. TCR reconstitution was successful in both transfectants and resulted in TCR protein and RNA levels similar to that of the parental MOLT-13 cell line. These cell lines could be activated through their receptors as assessed by increases in cytoplasmic free calcium. These studies imply that physical constraints cannot explain the observed chain pairing preferences. Other possible explanations are discussed.