T cells with α:ß or γ:δ receptors arise from a common progenitor
Lymphoid tissue; epidermis;
Intraepithelial (intestine, reproductive tract)
All lymphoid tissue
Distribution
(Periphery)
Innate immunityè recognize target directly (free Ag or Ag presented by non-MHC)
Acquired immunity
function
CD4- CD8-
CD4+ or CD8+
Expression of CD4 and CD8
HSP, non peptide ligand: phosphorylated ligand, lipid, unorthodox nucleotides, MHC IB
Peptide presented by MHC
Ag recognition
γ:δ
α:ß
Differences
Evidence for common lineage?
Rearrangement order
Signaling competition of TcRγ:δ and TcRß:preTα for lineage directing ligand