Selection of pulmonary CD4-, CD8-, alpha beta+ T cells expressing V beta 8 T cell receptors

The double negative (CD4-CD8-) alpha beta+ T cells constitute about 20% of all alpha beta+ T cells in murine lungs. We find that in BALB/c mice 60% of the double negative alpha beta+ pulmonary T cells express receptors of the V beta 8 family whereas only 33% of single positive (CD4+/CD8+) pulmonary T cells express V beta 8. However, in C57BL/6 mice, equal frequencies (25%) of double negative and single positive alpha beta+ pulmonary T cells express V beta 8. The high frequency of double negative V beta 8+ pulmonary T cells is dominantly inherited in (C57BL/6 X BALB/c) F1 offsprings. Further studies exclude the involvement of classic MHC region genes in determining the level of V beta 8 usage among double negative pulmonary T cells. Upon exposure to mycobacterial antigens, double negative alpha beta+ pulmonary T cells are co-enriched in vitro in parallel with gamma delta+ T cells.