Plasmatocyte depletion in larvae of Manduca sexta following injection of bacteria.

Injection of bacteria and bacterial cell walls into larvae of the tobacco hornworm elicits a rapid, specific depletion of plasmatocytes from circulation. Plasmatocyte depletion in response to injection of bacteria is dose dependent with a threshold for response between 10(3)-10(4) bacteria per insect and a maximal depletion at greater than 10(7) bacteria per insect. Injection of saline, latex beads that are phagocytized, or fragments of peptidoglycan that elicit antibacterial protein synthesis do not affect plasmatocyte abundance.