The lytic system ofHolothuria polii(Echinodermata): A review

Abstract

The Holothuria polii amebocytes produce two molecules of about 80 KDa molecular weight, serologically identical but with different chemico‐physical characteristics. A calcium‐dependent, heat‐sensible hemolysin (hemolysin 1) appears to be released under natural conditions, while a calcium‐independent, heat‐stable hemolysin (hemolysin 2) is produced under immunological stimulation. Both are able to interact with foreign cell surfaces probably through membrane sphingomyeline, producing serious damage leading to lysis. The molecules also act as opsonic elements. In the present paper a possible phylogenetic interpretation of the origin of these hemoly‐sins is discussed on the basis of similar effects observed in invertebrates and in relation to vertebrate complement and perforin.