INDUCTION OF TNF-ALPHA IN HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS BYTHE MANNOPROTEIN OF CRYPTOCOCCUS-NEOFORMANS INVOLVES HUMAN MANNOSE-BINDING PROTEIN
W. Chaka et al., INDUCTION OF TNF-ALPHA IN HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS BYTHE MANNOPROTEIN OF CRYPTOCOCCUS-NEOFORMANS INVOLVES HUMAN MANNOSE-BINDING PROTEIN, The Journal of immunology, 159(6), 1997, pp. 2979-2985
We have shown previously that specific receptors on PBMCs and a serum
factor other than Ab and complement are involved in the TNF-alpha resp
onse to cryptococcal mannoprotein (MP2). To characterize the mechanism
of MP2 recognition by PBMCs, 10(6) PBMCs were incubated with 25 mu g
of FITC-labeled MP2 in 10% normal human serum (1 h). The cells were an
alyzed by flow cytometry. FITC-MP2 binding was CaCl2 and temperature d
ependent and was enhanced by prestimulating PBMCs with unlabeled MP2.
Binding to PBMCs was specific, since unlabeled MP and mannan produced
dose-dependent inhibition. beta-Glucan laminarin produced background,
inhibition. mAbs against CD14, CD11b, and CD18 did not prevent FITC-MP
2 binding to PBMCs, implying that these receptors are not involved in
MP2 recognition by PBMCs. mAb against CD14 blocked (>90%) MP2-induced
TNF-alpha release by PBMCs, while mAbs against CD11b/CD18 caused no in
hibition. Removal of human mannose binding protein (hMBP) by preincuba
tion of serum with a specific mAb abrogated TNF-alpha induction by MP2
and strongly inhibited its binding to PBMCs. Recombinant hMBP enhance
d TNF-alpha induction by MP2 as well as binding of FITC-MP2 to PBMCs.
In addition, incubation of serum with MP2-coated beads and analysis by
SDS-PAGE resulted in the detection of a protein of approximately 33/3
4 kDa that could be partially removed by preincubating the serum with
hMBP mAb. We conclude that hMBP is involved in the binding of MP2 to P
BMCs and the release of TNF-alpha.