The species swine provides the only example for CD2+ and CD2- subsets of Ig-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 gamma/delta subdivides porcine CD2- lymphocytes into an epitope 86D+ minor and an 86D- major subset. Expression of distinct forms of the T cell receptor gamma/delta, 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.