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Related Concept Videos

Complement System01:27

Complement System

The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a membrane...
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Antibody Actions

Antibodies, or immunoglobulins, are critical players in the immune system's arsenal against invading pathogens. Produced by B cells and plasma cells, their primary role is to detect and bind to specific antigens, molecules found on the surface of pathogens like bacteria or viruses. Beyond antigen recognition, antibodies perform several vital functions that contribute to immune defense.
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Antimicrobial proteins are important components of the immune system. They aid the body in combating pathogens by either killing them directly or hindering their replication processes. Four main types of antimicrobial substances are interferons, the complement system, iron-binding proteins, and antimicrobial proteins.
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Hypersensitivity Reactions: Cytolytic Reactions01:01

Hypersensitivity Reactions: Cytolytic Reactions

Type II hypersensitivity involves IgG and IgM antibodies targeting cell surface antigens, leading to cell destruction. This can occur through complement activation, antibody-dependent cell-mediated cytotoxicity (ADCC), or acting as opsonins for phagocytosis. When excessive, these reactions cause significant tissue damage.Drug-induced hemolytic anemia is a common example, where drugs like penicillin or cephalosporins bind to red blood cells, forming drug-protein complexes. These complexes...
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Blood clotting or coagulation involves extrinsic and intrinsic pathways, which ultimately merge into the common pathway, forming a fibrin clot.
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Measuring the 50% Haemolytic Complement (CH50) Activity of Serum
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Published on: March 29, 2010

THE MECHANISM OF COMPLEMENT ACTION.

S C Brooks1

  • 1Harvard School of Tropical Medicine, Boston.

The Journal of General Physiology
|October 30, 2009
PubMed
Summary
This summary is machine-generated.

Ultra-violet light inactivates complement, reducing surface tension but not affecting heat sensitivity, suggesting it is not protein. This photoinactivation is pH-independent, leading to hypotheses about serum hemolytic substances.

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Area of Science:

  • Biochemistry
  • Immunology
  • Photochemistry

Background:

  • Complement is a crucial component of the immune system.
  • Previous research has explored complement's properties and interactions.

Purpose of the Study:

  • To investigate the effects of ultra-violet light on complement.
  • To elucidate the mechanisms underlying complement photoinactivation.
  • To propose hypotheses regarding the nature and function of hemolytic substances in serum.

Main Methods:

  • Exposure of complement to ultra-violet light.
  • Assessment of heat sensitivity after UV exposure.
  • Measurement of surface tension changes.
  • Analysis of hydrogen ion concentration (pH) variations.
  • Evaluation of complement activity at different pH levels.

Main Results:

  • Ultra-violet light exposure did not sensitize complement to heat, indicating it is not protein.
  • Photoinactivation of complement correlated with decreased surface tension.
  • Changes in hydrogen ion concentration were minimal (<0.05 pH) and did not cause photoinactivation.
  • High hydrogen ion concentrations (past the isoelectric point) permanently inactivated complement.

Conclusions:

  • Complement's non-protein nature is suggested by its heat sensitivity.
  • Ultra-violet light affects complement's surface tension and activity.
  • Hypotheses propose a photosensitive precursor and a lytic substance in serum, dependent on serum proteins for activity.