Human platelet Fc (IgG) receptor and its modulation

Conference · Sat Mar 01 04:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5006420

King, M; McDermott, P; Schreiber, A D

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-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:3
• Country of Publication: United States
• Language: English

Related Subjects

550901* -- Pathology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADP
AFFINITY
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION
BLOOD COAGULATION FACTORS
BLOOD PLATELETS
BODY FLUIDS
CALCIUM COMPOUNDS
CATIONS
CHARGED PARTICLES
COAGULANTS
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
FIBRINOGEN
GLOBULINS
HEMATOLOGIC AGENTS
HEMOSTATICS
HYDROLASES
IMMUNOGLOBULINS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAGNESIUM COMPOUNDS
MAMMALS
MAN
MATERIALS
MEMBRANE PROTEINS
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PATIENTS
PEPTIDE HYDROLASES
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
SERINE PROTEINASES
THROMBIN
TRACER TECHNIQUES
VASCULAR DISEASES
VERTEBRATES