Harvesting of leukocytes from intestinal lumen in murine giardiasis and preliminary characterization of these cells.

The aims of this study were to develop a method for harvesting leukocytes from the mouse small intestinal lumen and to identify leukocytes which enter the intestinal lumen of mice infected with Giardia muris. Giardia-infected and uninfected BALB/c mice were anesthetized, and the small intestine was removed. The intestinal lumen was then flushed with nutrient medium, and the luminal washings were found to contain substantial numbers of mononuclear leukocytes. The number of these cells harvested from the intestinal lumen of 24 mice infected with Giardia muris was 22 +/- 3 X 10(4) (mean value +/- standard error). Most of the cells were lymphocytes, although small numbers of macrophages were also obtained. By staining with monoclonal antibodies, approximately 50% of the intraluminal leukocytes were shown to be T lymphocytes. Similar numbers of mononuclear leukocytes were obtained from the intestinal lumen of Giardia-infected and uninfected mice. However, T lymphocytes and other mononuclear cells from infected animals were frequently observed in contact with Giardia trophozoites. This observation is consistent with the hypothesis that intraluminal leukocytes play a part in gastrointestinal immune defense.