scholarly journals 225 The role of PCγ2 in the in vitro activation of neutrophils by type VII collagen immune complexes

2021 ◽  
Vol 141 (10) ◽  
pp. S187
Author(s):  
V. Simon ◽  
A. Mócsai ◽  
K.P. Szilveszter
Keyword(s):  
Immune Complexes ◽  
Type Vii Collagen ◽  
In Vitro Activation

DETECTION OF INACTIVATED α2-MACROGLOBULIN (α2M) IN HUMAN PLASMA USING MONOCLONAL ANTIBODIES

1987 ◽  
Author(s):  
J Abbink ◽  
J Nuijens ◽  
C Huijbregts ◽  
E Hack
Keyword(s):  
Monoclonal Antibodies ◽  
Longitudinal Studies ◽  
Human Plasma ◽  
Dextran Sulfate ◽  
Optimal Conditions ◽  
Α2 Macroglobulin ◽  
In Vitro Activation

Monoclonal antibodies (mAbs) were raised against human a2M. Five mAbs that bound to α2M in ELISA were further analyzed by a radioimmunoassay (RIA) for their reaction with three types of α2M: native α2M, chemically inactivated α2M (iα2M) (methylamine treated), and proteolytically iα2M. One mAb reacted with all forms of α2M, while four mAbs bound both forms of ia2M but not native α2M. One of these latter mAbs (Ml) was used to develop a RIA (the Ml-assay) for the detection of iα2M in plasma: Ml coupled to Sepharose is incubated with the plasma to be tested, and bound iα2M is detected by a subsequent incubation with polyclonal 125I-anti-α2M antibodies. As little as 5 ng of iα2M can be detected with this assay in the presence of an excess of native α2M. This assay was then applied to measure inactivation of α2M in vitro and in vivo. In vitro activation of the contact system in plasma by dextran sulfate results in the inactivation of ca 10% of α2M. When blood from normal donors was collected under optimal conditions, about 0.5% of the total α2M content appeared to be iα2M. Longitudinal studies in patients (a.o. with septicaemie, during cardiopulmunary bypass) revealed that increased levels of iα2M occurred sporadically. The Ml-assay appears to be useful to monitor the role of α2M in human diseases.

In vitro activation of dibromoacetonitrile to cyanide: role of xanthine oxidase

2003 ◽  
Vol 77 (2) ◽  
pp. 86-93 ◽  
Author(s):  
Ahmed M. Mohamadin ◽  
Ashraf B. Abdel-Naim
Keyword(s):  
Xanthine Oxidase ◽  
In Vitro Activation

scholarly journals THE INTERACTION OF PARTICULATE HORSERADISH PEROXIDASE (HRP)-ANTI HRP IMMUNE COMPLEXES WITH MOUSE PERITONEAL MACROPHAGES IN VITRO

1972 ◽  
Vol 55 (3) ◽  
pp. 616-634 ◽  
Author(s):  
Ralph M. Steinman ◽  
Zanvil A. Cohn
Keyword(s):  
Horseradish Peroxidase ◽  
Immune Complexes ◽  
Half Life ◽  
Peritoneal Macrophages ◽  
Surface Complexes ◽  
Mouse Macrophages ◽  
Membrane Bound ◽  
Mouse Peritoneal Macrophages

The uptake, distribution, and fate of particulate horseradish peroxidase (HRP)-anti HRP aggregates has been studied in homogeneous monolayers of mouse macrophages in vitro. Macrophages rapidly interiorize the immune complexes after binding to the cell surface. The rate of interiorization is maximal for complexes formed in a broad zone of 4-fold antibody excess to equivalence and corresponds to a rate of 10% of the administered load/106 cells per hour. This rate is 4000-fold greater than the uptake of soluble HRP. The binding and endocytosis of HRP-anti HRP by macrophages is mediated by the trypsin insensitive Fc receptor. Cytochemically, intracellular HRP is localized within membrane bound vacuoles. After uptake of HRP, the enzymatic activity is degraded exponentially with a half-life of 14–18 hr until enzyme is no longer detectable. This half-life is twice as long as that previously observed for soluble uncomplexed HRP and is related to the combination of HRP with anti-HRP rather than the absolute amounts of enzyme or antibody ingested. The half-life of HRP-125I was 30 hr. Exocytosis of cell associated enzyme or TCA precipitable counts was not detected, nor were persistent surface complexes demonstrable. The extensive capacity of macrophages to interiorize and destroy large amounts of antigen after the formation of antibody illustrates a role of this cell in the efferent limb of the immune response.

On the Role of Platelet FcγRIIa Phenotype in Heparin-Induced Thrombocytopenia

1995 ◽  
Vol 74 (06) ◽  
pp. 1564-1572 ◽  
Author(s):  
John T Brandt ◽  
Craig E Isenhart ◽  
Jeanne M Osborne ◽  
Alaa Ahmed ◽  
Clark L Anderson
Keyword(s):  
Allelic Polymorphism ◽  
Normal Donor ◽  
Heparin Induced Thrombocytopenia ◽  
Aggregation Response ◽  
In Vitro Activation ◽  
Specific Variation ◽  
Activation Response ◽  
Murine Igg1

SummaryHeparin induced thrombocytopenia (HIT) is characterized by the formation of antibodies that activate normal donor platelets in vitro in the presence of heparin. We asked whether the commonly observed donor-specific variation in the platelet aggregation response to HIT antibodies is influenced by the density of FcγRII on platelets or by the Arg/His 131 allelic polymorphism of platelet FcγRII. We found that platelets with the His/Hisl31 FcγRII phenotype were unresponsive to HIT antibody (0/9) whereas platelets with the Arg/Argl31 phenotype responded well (7/9). His/Hisl31 platelets were largely unresponsive also to a murine IgG1 antiplatelet monoclonal antibody (UR1) known to activate platelets by FcγRII clustering. We then determined the frequency distribution of FcγRIIa Arg/His 131 phenotypes on a series of 200 patients evaluated for HIT and 100 non-thrombocytopenic hospitalized patients. The frequency of the His/Hisl31 phenotype was significantly increased (34.4%) in the 96 thrombocytopenic patients with HIT antibody compared to the 104 thrombocytopenic patients without HIT antibody and the 100 non-thrombocytopenic patients (∼19%). Thus, the FcγRII phenotype regulates the in vitro activation response of normal platelets to HIT antibody and is a risk factor for the thrombocytopenia of HIT

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