The in-vivo kinetics of lymphoblast localization in the small intestine.

We have studied the in-vivo kinetics of the accumulation of 125I-UdR labelled mesenteric lymphoblasts in the small intestine of mice. The efficiency with which the labelled cells were extracted from the blood and retained by the intestine was quantified by examination of the accumulations observed over the first 4 hr after cell transfer. The kinetic parameters for the uptake and retention of lymphoblasts determined from these early times were found to provide a good approximation to the entire time course of accumulation observed from 1 hr to 22 hr after cell transfer. For normal mice, approximately 1% of lymphoblasts delivered by the blood stream at any given time gained entry to the small intestine and were retained with an average half-time of 6.5 hr. We also studied the accumulation of lymphoblasts in the small intestine of mice undergoing a self-limited enteric infection with the nematode, Trichinella spiralis. There was a greater accumulation of lymphoblasts in the small intestine of these animals. This was the consequence of a prolongation of the half-time for retention of lymphoblasts within the intestine to 15 hr, rather than increased uptake of lymphoblasts from the blood. During a secondary infection with T. spiralis, the half-time for retention of lymphoblasts in the intestine was decreased to 3 hr. These studies show that viewing the accumulation of lymphoblasts as the result of a series of first order kinetic processes provides a suitable model for the migration of lymphoblasts to the small intestine.