Evidence for the presence of subpopulations of Arenicola marina coelomocytes identified by their selective response towards Gram+ve and Gram-ve bacteria.

In Arenicola marina (L.), in vitro attachment and phagocytosis of bacteria appears to be serum-independent and thus, non-specific. Mixtures of Gram+ve and Gram-ve bacterial species (Gram+ve/-ve, of two Gram+ve (Gram+ve/+ve) and of two Gram-ve bacterial species (Gram-ve/-ve)were overlaid on coelomocyte monolayers, in order to introduce competition for cell surface 'receptors'. An enhanced total phagocytosis was only recorded in the Gram+ve/-ve mixtures in comparison with their controls. The results are interpreted in terms of coelomocyte subpopulations and indicate that A. marina coelomocytes may possess specific carbohydrate/glycoprotein determinants capable of recognizing basic carbohydrate differences between the cell walls of Gram+ve and Gram-ve bacteria.