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Complement-like activity in the sea star, Asterias forbesi
L A Leonard1, J D Strandberg, J A Winkelstein
1Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205.
Developmental and Comparative Immunology
|January 1, 1990
Summary
Starfish coelomic fluid exhibits complement-like hemolytic activity against certain erythrocytes. This primitive immune system in Asterias also shows bactericidal properties, suggesting a functional role in innate immunity.
Area of Science:
- Marine biology
- Immunology
- Invertebrate physiology
Background:
- The complement system is a crucial part of innate immunity in vertebrates.
- Investigating complement-like pathways in invertebrates can reveal evolutionary insights into immune system development.
Purpose of the Study:
- To investigate the presence and characteristics of complement-like activity in the coelomic fluid of the starfish Asterias forbesi.
- To determine the functional capabilities, such as hemolytic and bactericidal activity, of this fluid.
Main Methods:
- Assaying hemolytic activity against various erythrocytes under different conditions (temperature, cation dependence).
- Testing for heat sensitivity, dose-response curves, and the effect of combining lytic and nonlytic fluids.
- Evaluating the consumption of activity by zymosan, proteases, and PMSF, and the effect of erythrocyte desialidation.
- Assessing bactericidal activity against Vibrio tubiashii.
Main Results:
- Cell-free coelomic fluid showed hemolytic activity against unsensitized rabbit erythrocytes, but not sheep erythrocytes.
- The activity was heat-sensitive, divalent cation-dependent (but not Ca++ or Mg++), and optimally assayed at 25°C.
- Activity was consumed by zymosan, pronase, and trypsin, and enzymatic desialidation of erythrocytes enhanced activation.
- Coelomic fluid demonstrated bactericidal activity against Vibrio tubiashii.
Conclusions:
- Asterias forbesi coelomic fluid possesses a primitive complement-like system with hemolytic and bactericidal functions.
- This system shares functional similarities with the vertebrate complement system, indicating an ancient evolutionary origin.