Microbial induced hemocytic immune reactions in chilopods

Hemocytic immune reactions were investigated in the chilopod myriapods Scolopendra cingulata and Lithobius forficatus. Hemocytes were taken into cell culture medium and challenged with latex beads, pre-fixed rat erythrocytes, or bacteria. After 1 to 4 hours in vitro hemocyte preparations were processed for electron microscopy. All tested particles were phagocytosed by the hemocytes and where possible degrated. In both animals the phagocytic cells inside the nodules were found to be tightly encircled by neighboring hemocytes. Aggregation of hemocytes and nodule formation significantly varied with the nature of the particles added. Bacteria stimulated nodules were larger, more compact and more regular in shape than aggregations formed in the presence of latex beads or fixed erythrocytes. The results are discussed with respect to investigations on cytokines, attraction factors and gap junctions in other invertebrates.