Resumo

CADAVID, LUIS F. The Evolution of Complex Systems: The Case of the Immune System in Animals. Acta biol.Colomb. [online]. 2009, vol.14, suppl.1, pp.247-254. ISSN 0120-548X.

The immune system in animals is composed by a series of cell and molecular mechanisms that coordinately maintain the physiological and genetic integrity of the organism. Traditionally, two classes of immunity have been considered, the innate immunity and the adaptive immunity. The former is ancestral, with limited variability and low discrimination. The latter is highly variable, specific and limited to jawed vertebrates. Adaptive immunity is based on antigen receptors that rearrange somatically to generate a nearly unlimited diversity of molecules. Likely, this mechanism of somatic recombination arose as a consequence of a horizontal transfer of transposons and transposases from bacterial genomes in the ancestor of jawed vertebrates. The recent discovery in jawless vertebrates and invertebrates of alternative adaptive immune mechanisms, suggests the necessity to consider new elements for the construction of an evolutionary model of the immune system in animals. Some of these elements are considered in this assay.

Palavras-chave : Evolution; immune system.

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