scholarly journals Binding of fluid-phase complement components C3 and C3b to human lymphocytes

1981 ◽  
Vol 198 (3) ◽  
pp. 509-518 ◽  
Author(s):  
E Sim ◽  
R B Sim
Keyword(s):  
Human Lymphocytes ◽  
Fluid Phase ◽  
Complement C3 ◽  
Human Tonsil ◽  
Complement Components ◽  
Sheep Erythrocytes ◽  
The Third ◽  
Complement Component C3 ◽  
Specific Manner ◽  
Third Component Of Complement

It is known that a population of B-lymphocytes has receptors for the third component of complement, C3, and that these lymphocytes may be identified by their ability to form rosettes with sheep erythrocytes coated with covalently bound fragments of complement component C3. Human tonsil lymphocytes, enriched for B-cells, form rosettes with sheep erythrocytes coated with antibody and complement components C1, C4b and C3b (EAC143b cells). Fluid-phase C3 will inhibit rosette formation between EAC143b and human tonsil lymphocytes over the same concentration range as fluid-phase C3b. C3 is not cleaved to C3b during incubation with lymphocytes or with lymphocytes and EAC143b cells. Fluid-phase 125I-labelled C3 and 125I-labelled C3b bind to lymphocytes in a specific manner. The characteristics of binding of both radioiodinated C3 and radioiodinated C3b are very similar, but the binding oc C3 is again not a result of cleavage to C3b. Salicylhydroxamic acid does not inhibit binding of 125I-labelled C3 to tonsil lymphocytes at concentrations that completely inhibit binding of 125I-labelled C3 to EAC142 cells via the nascent binding site of C3b. It is concluded that C3 and C3b share a common feature involved in binding to lymphocytes bearing receptors for the third component of complement.

scholarly journals The mechanism of action of the C3b inactivator (conglutinogen- activating factor) on its naturally occurring substrate, the major fragment of the third component of complement (C3b)

1975 ◽  
Vol 141 (5) ◽  
pp. 1221-1226 ◽  
Author(s):  
JD Gitlin ◽  
FS Rosen ◽  
PJ Lachmann
Keyword(s):  
Alternative Pathway ◽  
Fluid Phase ◽  
Complement C3 ◽  
Classical Pathway ◽  
Physiological Mechanisms ◽  
The Third ◽  
Immune Adherence ◽  
Normal Human ◽  
Molecular Nature ◽  
Third Component Of Complement

The fixation of the third component of complement (C3) results in many important biological phenomenon, among which are (a) immune adherence (1), (b) enhancement of phagocytosis (2,3), (c) the release of an anaphylatoxin which is a potent releaser of histamine (4), and (d) the feedback activation of the alternative pathway (5,6). The physiological mechanisms involving C3 fixation require the generation of a C3 convertase which may occur by two separate pathways. C3 convertase can be generated, in the form of C42, by the so-called classical pathway of activation or in the form C3b,B by the alternative or properdin pathway (7). In both cases, C3 is converted to C3b by cleavage of a small peptide, C3a. Normal human serum contains an inactivator of activated C3b. This C2b inactivator or conglutinogen-activating factor (KAF) has been shown to inhibit both immune hemolysis and the immune adherence properties of C3b and to cause cleavage of C3b in the fixed and fluid- phase stages (8-11). Although it is known that the C3b inactivator is not depleted during its reaction with C3b and that C3b treated with the C3b inactivator becomes extremely sensitive to proteolytic digestion by trypsin and trypsin-like enzymes (9), the exact molecular nature of the action of the C3b inactivator on C3b has not been studied. In an effort to delineate the products of this interaction, purified C3b and C3b inactivator were allowed to react for various specific lengths of time and the products of these reactions were then analyzed.

scholarly journals A receptor for the third component of complement in the human renal glomerulus

1975 ◽  
Vol 142 (4) ◽  
pp. 1029-1034 ◽  
Author(s):  
MC Gelfand ◽  
MM Frank ◽  
I Green
Keyword(s):  
Human Kidney ◽  
Complement C3 ◽  
Renal Diseases ◽  
Renal Glomerulus ◽  
Sheep Erythrocytes ◽  
Tissue Sections ◽  
The Third ◽  
Third Component Of Complement

In the course of studying the nature of mononuclear cellular infiltrates in tissue sections of human kidney it was noted that indicator sheep erythrocytes densely coated with the third component of complement (C3) specifically adhered to all of the glomeruli in the tissue sections. The deposition of complement (C) within the glomerulus is a feature of many immunologically related renal diseases (1,2), yet the precise mechanism by which C is deposited remains unexplained. We feel that this observation, suggesting the presence of a receptor for C, is, therefore, of particular interest.

scholarly journals Analysis of the interactions between properdin, the third component of complement (C3), and its physiological activation products

1988 ◽  
Vol 252 (1) ◽  
pp. 47-54 ◽  
Author(s):  
T C Farries ◽  
P J Lachmann ◽  
R A Harrison
Keyword(s):  
Ionic Strength ◽  
Alternative Pathway ◽  
Fluid Phase ◽  
Complement C3 ◽  
Initial Product ◽  
Native Form ◽  
Factor I ◽  
The Third ◽  
Activation Products ◽  
Third Component Of Complement

The interactions of properdin with both surface-bound and fluid-phase C3 (the third component of complement) and its activation products have been investigated by using a purified preparation of the ‘native’ form. At physiological ionic strength, a weak interaction with cell-bound C3b (the larger activation fragment of C3) could be demonstrated. In the presence of Factor B this interaction was enhanced, and further enhancement was seen when C3bBb sites were formed on the erythrocytes. The avidities of properdin for cell-bound iC3b (the initial product of Factors I and H action on C3b) and C3b were compared at low ionic strength, with that measured for iC3b being less than that for C3b. In contrast, the affinities of properdin for fluid-phase C3b, iC3b and C3c (the larger product of Factors I and H or CR1 (the C3b receptor) action on iC3b) were all very similar, and apparently much weaker than that for cell-bound C3b. No interaction with either native C3 or, more surprisingly, C3i (haemolytically inactive C3) could be detected. Properdin also inhibited Factor I binding to, and action upon, cell-bound C3b, but did not inhibit Factor I action on fluid-phase C3b. These data permit a more detailed description of the roles of properdin in the alternative pathway of complement activation, emphasizing its importance in concentrating activation at the activating surface.

scholarly journals THE BIOLOGIC SIGNIFICANCE OF THE THIRD COMPONENT OF COMPLEMENT (C3) IN NONIMMUNE HOST DEFENSES

1974 ◽  
Vol 8 (4) ◽  
pp. 421-421
Author(s):  
Jerry A Winkelstein ◽  
Mary Ruth Smith ◽  
Hyun S Shin ◽  
David H Carver
Keyword(s):  
Complement C3 ◽  
Host Defenses ◽  
The Third ◽  
Third Component Of Complement

scholarly journals Metabolism of the third component of complement (C3) in patients with rheumatoid arthritis

1972 ◽  
Vol 15 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Arthur Weinstein ◽  
Keith Peters ◽  
David Brown ◽  
Rodney Bluestone
Keyword(s):  
Rheumatoid Arthritis ◽  
Complement C3 ◽  
The Third ◽  
Third Component Of Complement

Family studies on the third component of complement (C3), 6h1-antitrypsin polymorphism (locus E1 and E2) in the area of Marburg (Germany)

1972 ◽  
Vol 17 (1) ◽  
pp. 85-87 ◽  
Author(s):  
H. W. Goedde ◽  
L. Hirth ◽  
H. -G. Benkmann ◽  
S. Singh ◽  
G. G. Wendt
Keyword(s):  
Family Studies ◽  
Complement C3 ◽  
The Third ◽  
Third Component Of Complement

Effect of Aging of Serum on Quantitation of Complement Component C3

1972 ◽  
Vol 18 (12) ◽  
pp. 1485-1487 ◽  
Author(s):  
N C Davis ◽  
C D West ◽  
M Ho
Keyword(s):  
Previous History ◽  
Complement C3 ◽  
Antigenic Determinants ◽  
Breakdown Product ◽  
Variable Degree ◽  
Complement Component C3 ◽  
Apparent Concentration ◽  
History Of ◽  
Monospecific Antisera ◽  
Third Component Of Complement

Abstract Concentrations of the third component of complement (C3, β1C globulin) in serum may vary considerably in patients with certain diseases. Its accurate measurement is therefore important medically. For some time it has been recognized that the C3 in serum stored at room temperature breaks down into two proteins, β1A and α2D. Monospecific antisera have been made to the three antigenic determinants of C3, designated A, B, and D. An anti-C3 supplied commercially is monospecific for the A determinant, which is shared by C3 and its breakdown product β1A. With C3 breakdown and formation of β1A, depletion of antibody to the A determinant is increased to 1.6 times the depletion by native C3. Therefore, the previous history of a serum can affect the "apparent" concentration of C3, with values spuriously increased to a variable degree, in serum that has been stored. The effect of time, temperature, and conditions of storage on this increase are discussed.

scholarly journals Biosynthesis of the third component of complement (C3) by the human monocytic-cell line U-937 Induction by phorbol myristate acetate

1986 ◽  
Vol 239 (3) ◽  
pp. 711-716 ◽  
Author(s):  
S Bengio ◽  
D Gilbert ◽  
P Peulve ◽  
M Daveau ◽  
M Fontaine
Keyword(s):  
Phorbol Myristate Acetate ◽  
Complement C3 ◽  
Enzyme Linked Immunosorbent Assay ◽  
Haemolytic Activity ◽  
Subunit Structure ◽  
Single Chain ◽  
Myristate Acetate ◽  
Monocytic Cell ◽  
The Third ◽  
Third Component Of Complement

Phorbol myristate acetate (PMA)-stimulated human monocyte-like cells (U-937) were found to synthesize the third component of complement (C3), as shown by enzyme-linked immunosorbent assay and immunoprecipitation from [35S]methionine-labelled culture supernatants. C3 synthesis occurred at a rate of about 160 ng of C3/24 h per 10(6) cells on day 7 after addition of PMA; it was blocked by cycloheximide treatment and was restored after removal of the inhibitor. SDS/polyacrylamide-gel-electrophoretic analysis of the immunoprecipitated protein showed that the size and subunit structure of the newly synthesized C3 were identical with those of plasma C3, and that a single-chain intracellular precursor was present in the cell lysates. Haemolytic assays showed that the synthesized C3 fully expressed functional activity in early culture within 4 h. After longer culture, a loss of haemolytic activity was observed. The possibility that newly secreted C3 is cleaved by U-937 cells themselves was suggested.

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