TY - JOUR
T1 - A role for lipid rafts in C1q-triggered O2- generation by human neutrophils
AU - Otabor, Iyore
AU - Tyagi, Shivraj
AU - Beurskens, Frank J.M.
AU - Ghiran, Ionita
AU - Schwab, Pascale
AU - Nicholson-Weller, Anne
AU - Klickstein, Lloyd B.
N1 - Funding Information:
We thank the following investigators for their generous gifts of reagents: T.A. Springer (Center for Blood Research, Harvard Medical School, Boston, MA) for mAb CBR-M1/5; M. Robinson (Celltech Group, London) for mAb KIM-127; Daniel Simon (Brigham and Women’s Hospital, Boston, MA) for mAb LPM19c; and Robert Rothlein for recombinant soluble ICAM-1. This work was supported by a Pilot Grant from the Harvard Digestive Disease Center (P30 DK34845) to IG and NIH RO1 grants AI142987 (A.N.W.), AR47243 (L.B.K.).
PY - 2004/6
Y1 - 2004/6
N2 - Calreticulin, a candidate C1q receptor, was shown recently to be present on the surface of human neutrophils in association with glycosylphosphatidylinositol (GPI) anchored proteins, particularly CD59. In this study, we show that antibodies to CD59, as well as to every other GPI-anchored protein tested, inhibited the C1q-triggered release of O2- from PMN. Methyl β cyclodextrin (MβCD) treatment of the cells to disrupt lipid rafts also prevented C1q-triggered O2- production. β2 integrin-dependent co-stimulation is required for O2- production from PMN, however MβCD had no effect on LFA-1 or Mac-1-mediated adhesion, soluble iC3b binding to PMN, or spreading and migration, all of which suggested that PMN integrin function remained intact. Flow cytometric analysis of PMN treated with MβCD showed upregulation of PMN granule-associated integrins and a corresponding increase in integrin activation-reporter epitopes, in contrast to the decreased expression of GPI-anchored antigens. These data support a model where lipid rafts and their associated GPI-anchored proteins are critical for C1q-triggered O 2- production, consistent with a model where calreticulin serves as the C1q receptor for O2- production from PMN.
AB - Calreticulin, a candidate C1q receptor, was shown recently to be present on the surface of human neutrophils in association with glycosylphosphatidylinositol (GPI) anchored proteins, particularly CD59. In this study, we show that antibodies to CD59, as well as to every other GPI-anchored protein tested, inhibited the C1q-triggered release of O2- from PMN. Methyl β cyclodextrin (MβCD) treatment of the cells to disrupt lipid rafts also prevented C1q-triggered O2- production. β2 integrin-dependent co-stimulation is required for O2- production from PMN, however MβCD had no effect on LFA-1 or Mac-1-mediated adhesion, soluble iC3b binding to PMN, or spreading and migration, all of which suggested that PMN integrin function remained intact. Flow cytometric analysis of PMN treated with MβCD showed upregulation of PMN granule-associated integrins and a corresponding increase in integrin activation-reporter epitopes, in contrast to the decreased expression of GPI-anchored antigens. These data support a model where lipid rafts and their associated GPI-anchored proteins are critical for C1q-triggered O 2- production, consistent with a model where calreticulin serves as the C1q receptor for O2- production from PMN.
KW - GPI
KW - LFA-1
KW - Mac-1
KW - Methyl-β-cyclodextrin
KW - MβCD
KW - O
KW - PMN
KW - complement receptor 3 or CD11b/CD18
KW - glycosylphosphatidylinositol
KW - leukocyte function antigen-1 or CD11a/CD18
KW - polymorphonuclear leukocyte or neutrophil
KW - superoxide
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U2 - 10.1016/j.molimm.2004.03.029
DO - 10.1016/j.molimm.2004.03.029
M3 - Article
C2 - 15159064
AN - SCOPUS:2442680524
SN - 0161-5890
VL - 41
SP - 185
EP - 190
JO - Molecular Immunology
JF - Molecular Immunology
IS - 2-3
ER -