A novel granulocyte-specific α integrin is essential for cellular immunity in the silkworm Bombyx mori

Haemocytes play crucial roles in immune responses and survival in insects. Specific cell markers have proven effective in clarifying the function and haematopoiesis of haemocytes. The silkworm Bombyx mori is a good model for studying insect haemocytes; however, little is known about haemocyte-specific markers or their functions in silkworm. In this study, we identified the α subunit of integrin, BmintegrinαPS3, as being specifically and highly expressed in silkworm haemocytes. Immunofluorescence analysis validated the specificity of BmintegrinαPS3 in larval granulocytes. Further analyses indicated that haemocytes dispersed from haematopoietic organs (HPOs) into the circulating haemolymph could differentiate into granulocytes. In addition, the processes of encapsulation and phagocytosis were controlled by larval granulocytes. Our work demonstrated that BmintegrinαPS3 could be used as a specific marker for granulocytes and could be applied to future molecular cell biology studies.