BACTERIAL LIPOPOLYSACCHARIDE CONTAMINATION OF COMMERCIAL COLLAGEN PREPARATIONS MAY MEDIATE DENDRITIC CELL MATURATION IN CULTURE

Dendritic cells (DC) are potent antigen presenting cells, which are re sponsible for the initiation of naive T and T-dependent immune respons es. The present studies were based upon recent reports that commercial collagen I preparations induce the maturation of human DC in vitro. W e show that human blood monocyte-derived (GM-CSF and IL-4 cultured) DC pulsed on collagen I-coated plates undergo a dose-dependent increase in stimulatory capacity in oxidative mitogenesis assays. This is accom panied by the upregulation of costimulatory molecules (CD40, CD80, CD8 6), CD25, ICAM-1 and the DC-specific marker CD83. The maturation effec t is more potent than TNF-alpha, which is a known mediator of DC funct ion. However, bacterial lipopolysaccharide (LPS), a powerful inducer o f DC maturation, was found to be present at very high levels in one co mmercial collagen solution that was tested. The effect of LPS upon DC maturation was similar to culture with collagen. Furthermore, a differ ent collagen I preparation with low levels of LPS contamination was le ss effective at inducing DC maturation, while spiking the collagen sol ution with LPS prior to plastic coating equalised these effects. Final ly, human monocyte-derived DC were found not to express typical collag en receptors VLA-1, 2 and 3. We therefore propose that LPS contaminati on may at least partially explain reported collagen I induced DC matur ation. (C) 1998 Elsevier Science B.V. All rights reserved.