Human platelet Fc (IgG) receptor and its modulation
The authors demonstrated that IgG oligomers bind to washed human platelets (P) by an Fc dependent process optimally at low ionic strength (/sup +/0.07) in 3 hrs at 4/sup 0/, while IgG monomer binds immeasurably. The authors studied the modulation of this Fc (IgG) binding site (Rc) on P by measuring /sup 125/I-IgG trimer binding to P at equilibrium and assessing Rc number of affinity. At ..mu.. = 0.07, P expressed 2 fold more Rc than at ..mu.. = 0.15, without a change in affinity; this effect was reversed upon re-exposure of P to ionic strength ..mu.. = 0.15. Equal numbers and affinities of Rc were observed in the presence of either 2mM EDTA, 2 mM EGTA or 2 mM EGTA + 2 mM Mg/sup + +/. Cytochalasin B (10 ..mu..g/ml) did not alter Rc (4987 sites/P, Ka = 0.9 x 10/sup 7/M/sup -1/ vs 5098 sites/P, Ka = 1.1 x 10/sup 7/M/sup -1/). Incubation with P alloreactive plasma at a concentration which depleted 33% of plasma C3, decreased Rc by 50%. However, activation of P by 10..mu..M ADP with Ca/sup + +/, Mg/sup + +/ and 100 ..mu..g/ml fibrinogen did not affect Rc number of affinity (2825 sites/P, Ka = 1.1 x 10/sup 7/M/sup -1/ vs 2551 sites/P, Ka = 0.9 x 10/sup 7/M/sup -1/). Thrombin (0.01 - 10 U/ml) also did not alter the number or affinity of Rc. P from 2 patients with thrombastenia expressed normal Rc number and affinity. Binding of IgG trimer to P occurs independent of actin filament interaction, Mg/sup + +/, modulation of P by ADP or thrombin, and of GPIIb/IIIa orGPIIb/IIIa-fibrogen interaction.
- Research Organization:
- Univ. of Pennsylvania School of Medicine, Philadelphia
- OSTI ID:
- 5006420
- Report Number(s):
- CONF-8604222-; TRN: 86-037031
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Protein kinase activity associated with Fc. gamma. /sub 2a/ receptor of a murine macrophage like cell line, P388D/sub 1/
Regulation of phosphoinositide hydrolysis and fibrinogen receptor expression by GTP regulatory protein(s) in isolated platelet membranes
Related Subjects
BLOOD PLATELETS
BLOOD COAGULATION
IMMUNOGLOBULINS
BIOCHEMICAL REACTION KINETICS
RECEPTORS
ADP
AFFINITY
CALCIUM COMPOUNDS
CATIONS
FIBRINOGEN
IODINE 125
MAGNESIUM COMPOUNDS
MAN
PATIENTS
THROMBIN
TRACER TECHNIQUES
VASCULAR DISEASES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION FACTORS
BODY FLUIDS
CHARGED PARTICLES
COAGULANTS
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
GLOBULINS
HEMATOLOGIC AGENTS
HEMOSTATICS
HYDROLASES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
SERINE PROTEINASES
VERTEBRATES
550901* - Pathology- Tracer Techniques