SUBPOPULATIONS OF HEMOCYTES IN THE ADULT AND DEVELOPING MARINE MUSSEL, MYTILUS-EDULIS, IDENTIFIED BY USE OF MONOCLONAL-ANTIBODIES

Monoclonal antibodies specific for haemocyte sub-populations in the mu ssel, Mytilus edulis, were raised by use of separated basophilic and e osinophilic cell types as antigens. The antibodies could be broadly di vided into 3 groups, reactive with sub-populations of (1) basophilic g ranular haemocytes, (2) basophilic granular and hyaline cells and (3) eosinophilic granular cells. Non-selective antibodies staining all hae mocytes were also generated. The antibodies bound to epitopes of diffe ring molecular masses and, at the ultrastructural level, reacted princ ipally with the granules of the haemocyte sub-populations, The antibod ies were used to investigate haemocyte function and ontogeny and to te st reactivity with haemocytes from mussels subject to varying degrees of pollution stress. Five antibodies showed reactivity with cells from the trochophore and veliger larvae of M. edulis, indicating that epit opes on adult mussel haemocytes are also present at much earlier stage s in the life history. Reactivity with the larval stages was most prev alent with non-selective antibodies and those selective for basophilic haemocytes. When mussels from different sites were examined, both imm unocytochemistry and ELISA showed reduced expression of a 140 kDa epit ope in the haemocytes of mussels subject to greater contaminant loads. These results show that the monoclonal antibodies of the present stud y are valuable both in tracing immune-cell development and in detectin g molecular changes under conditions of stress.