Role of the macrophage in the translocation of intestinal bacteria
C. L. Wells, M. A. Maddaus and R. L. Simmons
To clarify the role of the macrophage in the translocation of intestinal
bacteria, groups (n = 10) of Swiss Webster mice (Immunocompetent) and
C3H/HeJ mice (macrophage defective) were given bacitracin/streptomycin in
their drinking water to eliminate the majority of the intestinal
microflora. These mice were then "monoassociated" with a
streptomycin-resistant strain of Escherichia coli. Forty-eight hours later,
E coli was present in all animals at a concentration of 10(11)/g of cecum.
In four separate experiments, E coli was recovered from 100% of the
mesenteric lymph nodes (MLNs) of the immunocompetent Swiss Webster mice and
from 10%, 40%, 30%, and 50% of the MLNs of macrophage-defective C3H/HeJ
mice. Swiss Webster mice were then similarly monoassociated by antibiotic
decontamination followed by administration of antibiotic-resistant,
fluorescein-labeled E coli in their drinking water; cohort groups of mice
were given fluorescein-labeled latex beads (1 micron in diameter) in their
drinking water. Two, four, and 11 days later, the MLNs were removed and
single cell suspensions were analyzed in the fluorescence-activated cell
sorter. The fluorescein label was detected exclusively in the macrophage
(esterase-positive) population. These results support the hypothesis that
intestinal macrophages may play a key role in the transport of intestinal
particles (including bacteria) into extraintestinal sites.
