γ/δT-Lymphocyte Subsets in Swine

Abstract

Evidence for fundamental differences in the overall organization of mammalian lymphoreticular systems dates back to the work of CHIEVITZ (1881) demonstrating microanatomical inversion of swine lymph node tissues in that B- and T-lymphocyte lodging areas are interchanged. Associated with this is an altered route of lymphocyte recirculation: entry and exit both take place via venules, causing efferent lymph to be almost acellular. The specialty of the porcine immune system extends also to the composition of the lymphocyte pool. In addition to B and classical T lymphocytes, a third major population of so-called ‘null lymphocytes’ was distinguished by the absence of surface Ig and by its inability to form xenoerythrocyte rosettes (BINNS 1982). Recent work of our group has classified these formerly enigmatic cells as a CD2^- CD4^- CD8^- subpopulation of T lymphocytes, encompassing two subsets of γ/δ T lymphocytes (SAALMÜLLER et al. 1989; HIRT et al. 1990).