Selective localization of mesenteric lymphoblasts in mucosal tissues: effects of altering the number of donor lymphoblasts.

We have studied the effect of altering the numbers of lymphoblasts from the mesenteric lymph node (MLN) transferred into syngeneic female CBA/J mice on their distribution and abundance 24 hr later. The frequency of [3H]-thymidine-labelled donor MLN cells in the recipient small intestine and lungs was directly related to the numbers transferred. Of the donor MLN lymphoblasts in the small intestine, 62.5% +/- 0.9% were seen in the basal lamina propria, 32.5% +/- 0.9% in the villus lamina propria and 5% +/- 0.6% in the epithelium. Of the MLN lymphoblasts localizing in the lungs, 90% +/- 2.3% were in the parenchyma while 6.7% +/- 1.8% and 3.3% +/- 1.0% appeared in the bronchus-associated lymphoid tissue (BALT) and the bronchial epithelium, respectively. Although few peripheral lymph node (PLN)- derived lymphoblasts localized in the small intestine, the numbers of PLN lymphoblasts in the lungs were similar to those observed after transfer of comparable doses of MLN lymphoblasts. However, PLN Lymphoblasts were found only in the pulmonary parenchyma and did not appear in either BALT or bronchial epithelium. These data suggest that the number of MLN, but likely not PLN, lymphoblasts in the circulation, directly influences the numbers of lymphoblasts which localize in intestinal mucosa, BAlt and bronchial epithelium. Even at the highest doses of MLN lymphoblasts transferred we could not saturate the capacity of these tissues to accommodate MLN lymphoblasts nor was their intra-intestinal distribution altered.