Proliferating intestinal γ/δ T cells recirculate rapidly and are a major source of the γ/δ T cell pool in the peripheral blood

Abstract

The proliferation, recirculation and repertoire of gut-derived γ/δ T cells were studied in pigs in vivo. Proliferating γ/δ T cells (detected by BrdU labeling) are present in all intestinal compartments. In the gut lymph ∼0.5% of all γ /δ T cells were proliferating. These gut-derived BrdU+ γ/δ T cells re-enter the intestinal tissues, and re-appear in the intestinal lymph far more often than other cells: about 22% of i.v.-injected BrdU+ γ/δ T cells were recovered again from the intestinal lymph within 72 h (compare with BrdU+ B cells 2%, and other BrdU+ T cells 10%). The contribution of the gut to the migrating γ/δ T cell pool in the blood became obvious: the proportion of BrdU+ γ /δ T cells was three-times larger in control versus cannulated pigs. In 9-month-old pigs, clonally expanded T cells were identified in the intestine by complementarity-determining region 3 spectratyping of TCR-δ transcripts. Such expansions were not visible in the blood or intestinal lymph. The distribution of γ/δ T cells within the intestinal tract is likely to depend to a large degree on the proliferation and the migratory properties of these cells which are different to those of α/β T cells and B lymphocytes.