Capacity of "transplanted" lymphocytes to traverse the intestinal epithelium of adult rats.

Suspensions of viable lymph node cells (LNCs), both unlabeled and 3H-uridine labeled, from adult Fischer (FI) rats were inoculated into the lumens of established, surgically isolated segments of ileum in adult (FI x DA)F1 hybrid hosts. Vascular, lymphatic, and nerve supplies of the isolated segment were preserved. It was reasoned that subsequent hypertrophy of the draining mesenteric LN complex, on an immunogenetically specific basis (attributable to graft-versus-host (GVH) reactivity) and histological identification of labeled lymphoid cells in the intestinal wall of the isolated segment, would be indicative of the passage of inoculated cells across the intestinal epithelium. It was found that host mesenteric LNs were significantly larger on the 8th postinoculation day in animals that received 100 x 10(6) or 300 x 10(6) FI LNCs than in animals that were given similar numbers of syngeneic F1 hybrid cells (controls). This lymph node hypertrophy was dosage dependent and favorably influenced by the presence of Peyer's patches. The results of experiments involving introduction of 3H-uridine-labeled cells into isolated ileal segments and subsequent radioautography corroborated the conclusion that lymphocytes deposited in the intestinal lumen can gain access to host tissues, i.e., they are "naturally transplanted."