Hemolymph transfer as an assay for immunorecognition in the cockroach Periplaneta americana and the locust Schistocerca gregaria.

A quantitative assay for measuring the number of hemocytic nodules formed in response to foreign particles and soluble molecules has been used, in the locust Schistocerca and the cockroach Periplaneta, to investigate the response to transferred hemolymph. Xenogeneic test particles, rabbit neutrophil leukocytes, stimulate formation of nodules when injected into both insect species, compared with saline-injected controls. However, the number of nodules formed in the locust in response to cockroach hemolymph is significantly reduced compared with the response to other xenogeneic cells, and it is suggested that, in view of the strong reactivity of cockroach hemocytes to locust hemolymph and plasma, a graft-versus-host response might be occurring in the recipient locust. Whole hemolymph transferred allogeneically between Periplaneta, or xenogeneically from Blatta to Periplaneta, does not stimulate a response in the recipient. This corresponds well with results from other assays for immunorecognition of transplants and is further confirmation that allogeneic and, in some combinations xenogeneic, recognition is absent in insects.