BACTERICIDAL ACTIVITY OF THE BLOOD OF ACTIVELY IMMUNIZED WAX MOTH LARVAE

Abstract

The blood of normal wax moth larvae is not bactericidal for Pseudomonas aeruginosa. The blood becomes moderately bactericidal when larvae are actively immunized against P. aeruginosa. This activity was measured by a modification of Nagington's technique for the estimation of typhoid antibody. Bactericidal activity appears to be the only measurable type of antibody response against P. aeruginosa. Cell-free blood was as active as whole blood; 0.02 ml of immune serum kills about 1000 organisms. The blood of normal wax moth larvae is bactericidal for Shigella dysenteriae but the blood of insects immunized against either this organism or P. aeruginosa shows no increase in activity against S. dysenteriae. A number of non-specific agents, both protein and non-protein, did not stimulate bactericidal activity in serum after their injection into normal larvae. Immune sera prepared against some strains of P. aeruginosa were not active against other strains. Storage at 37 °C or absorption with zymosan both result in blackening of immune blood and loss of bactericidal activity. Bactericidal activity is evident only during the immune state of the insect, i.e. from about 18 hours until the third day after vaccination; it develops at the same time that inhibition of melanization was observed in the blood from vaccinated larvae.