Induction of immunity by latex beads and by hemolymph transfer in Galleria mellonella.

Injection of sterile latex beads into the hemocoel of last instar larvae of Galleria mellonella provoked a strong defense reaction. Cellular defense by hemocytes was followed by enhanced antibacterial activity in hemolymph. Latex-injected insects showed increased survival rates after a challenge injection with high doses of bacteria. Factors which stimulate the production of antibacterial activity could be demonstrated soon after injection by transfer of hemolymph from preinjected to untreated larvae. A large induction capacity in donor hemolymph was accompanied by a strong decrease in the total hemocyte count of free floating hemocytes, resulting from a decrease in number of plasmatocytes and granular cells, the cell types involved in the cellular defense against the injected latex beads. The results presented support the hypothesis that during cellular defense reactions, factors are released from the hemocytes which stimulate the production of antibacterial substances.