Distinct γ/δ T cell receptors define two subsets of circulating porcine CD2−CD4−CD8− T lymphocytes*

Abstract

The species swine provides the only example for CD2⁺ and CD2⁻ subsets of lg⁻CD4⁻CD8⁻ lymphocytes with the propensity for homing to lymphoid tissue (Saalmüller et al., Eur. J. Immunol. 1989. 19: 2011). That the CD2⁻CD4⁻CD8⁻ lymphocytes are bare of marker molecules that typify T lymphocytes raised the question of whether or not this cell type is descended from the T lymphocyte differentiation lineage. It is documented that expression of a phylogenetically conserved external epitope of T cell receptor γ/δ subdivides porcine CD2⁻ lymphocytes into an epitope 86D⁺ minor and an 86D⁻ major subset. Expression of distinct forms of the T cell receptor γ/δ, disulfide‐bonded N‐glycosylated surface heterodimers of under reducing conditions 38/40 and 37/40 kDa, respectively, hallmarks the CD2⁻86D⁺ and CD2⁻86D⁻ subsets both as T lymphocytes.