Regional blood flow and the localization of lymphoblasts in the small intestine of the mouse. I. Examination of normal small intestine.

The localization of 125I-UdR-labelled mesenteric lymphoblasts and the fraction of the cardiac output delivered to the small intestine was investigated in mice. When different regions of the small intestine were examined, the proportional delivery of the cardiac output and the localization of lymphoblasts were found to vary along the length of the small intestine. A significant correlation between these two phenomena was identified when both lymphoblast localization and the distribution of the cardiac output within the small intestine were studied concurrently. The intestinal localization of populations of unseparated or T-enriched mesenteric lymphoblasts and peripheral lymphoblasts all showed a similar degree of correlation with the fraction of the cardiac output delivered along the small intestine in spite of marked differences in their proclivity to accumulate in the gut. We conclude that there is an important relationship in normal animals between the level of lymphoblast accumulation within a particular region of the small intestine and the delivery of blood-borne cells to that region. This relationship could provide a physiological explanation for a antigen-independent yet non-uniform distribution of effector cells within the lamina propria of unimmunized animals.