Mc. Grimm et al., EVIDENCE FOR A CD14(-DISEASE MUCOSA-IMPLICATIONS FOR PATHOGENESIS() POPULATION OF MONOCYTES IN INFLAMMATORY BOWEL), Clinical and experimental immunology, 100(2), 1995, pp. 291-297
Lipopolysaccharide (LPS) is abundant in the intestinal lumen. CD14 is
the receptor for the LPS-LPS binding protein complex, and its presence
on mononuclear phagocytes allows cell activation by pg/ml concentrati
ons of LPS. We have shown that the recently recruited blood monocyte i
n inflammatory bowel disease mucosa is CD14(+). This study examined th
e expression of CD14 on macrophages in inflamed (n = 13) and uninflame
d (n = 7) intestine by immunohistochemistry, and on disaggregated lami
na propria mononuclear cells (12 from inflamed, 17 from uninflamed int
estine) and peripheral blood mononuclear cells (n = 26) by flow cytome
try, using a panel of three MoAbs directed against CD14. Immunohistoch
emistry revealed that 3.7% of macrophages in uninflamed intestine were
CD14(+), while 25.1% of macrophages in active inflammatory bowel dise
ase expressed CD14 (P < 0.02). Flow cytometry demonstrated that CD14 e
xpression by macrophages from Crohn's disease and ulcerative colitis w
as augmented significantly (P = 0.02 and P = 0.01, respectively) compa
red with uninflamed intestine, with a discrete population of macrophag
es in inflammatory bowel disease, not present in normal intestine, whi
ch strongly expressed CD14. The characteristically high levels of CD14
on blood monocytes were unaffected by the presence of intestinal infl
ammation. Given the exposure of lamina propria cells to LPS present in
the lumen of the terminal ileum and colon, the increased numbers of C
D14(+) macrophages in inflammatory bowel disease may result in greatly
increased production of inflammatory mediators, thereby suggesting a
mechanism for the perpetuation of mucosal inflammation.