The immune system of spiders

Abstract

The immune system of spiders is localised in their hemocytes and reacts very fast to an invasion by pathogens and to injuries by releasing several compounds into the hemolymph. The immune response comprises (1) phagocytosis, nodulation and encapsulation of invaders, (2) the regulation of hemocyanin/phenoloxidase to produce melanin which destroys pathogens, (3) a clotting cascade to stop hemolymph loss and immobilise invaders and (4) the constitutive production of antimicrobial peptides. So far four different antimicrobial peptide groups have been identified in spiders. Firstly, six similar defensins have been detected in different spider groups. A second group of antimicrobial peptides comprises several glycine-rich peptides (acanthoscurrins and ctenidins), a third group of small cysteine-rich peptides contains gomesin, an 18 amino acid residue peptide, and as a fourth group, a hemocyanin fragment has been identified.