LAUSR

Abstract The identification of molecular markers considerably facilitated the classification and functional analysis of blood cell types. Apis mellifera hemocytes have been classified by morphological criteria and lectin binding properties; however, the use of molecular markers has been minimal. Here we describe a monoclonal antibody to a non‐phagocytic subpopulation of A. mellifera hemocytes and to a constituent of the hemolymph clot. We demonstrate that the antibody identifies the A. mellifera hemolectin, a protein carrying human von Willebrand factor homology domains, characteristic of proteins involved in blood coagulation and platelet aggregation in mammals. Hemolectin expressing A. mellifera hemocytes contain the protein as cytoplasmic granules and contribute to the formation of a protein matrix, building up around foreign particles. Consequently, hemolectin as a marker molecule reveals a clear functional heterogeneity of hemocytes, allowing for the analytical separation of hemocyte classes, and could promote the molecular identification of hemocyte lineages in A. mellifera. Graphical abstract Figure. No Caption available. HighlightsClassification of honey bee hemocytes is achieved by a novel monoclonal antibody.The honey bee possesses three main functionally different hemocyte classes.The hemocyte classes are the aggregating, the phagocyting and the melanizing cells.The novel antibody reacts with the hemolectin in aggregating plasmatocytes.Monoclonal antibodies can be applied to separate hemocyte classes in the honeybee.