Local reactions of the saponin Quil A and a Quil A containing iscom measles vaccine after intramuscular injection of rats: a comparison with the effect of DPT-polio vaccine.

A short-term toxicity study was performed to investigate local reactions and hematological changes after im injection of Quillaia A (Quil A; 50 or 600 micrograms/ml) an essential component of an immunostimulating complex (iscom), a novel form of a subunit vaccine, and of iscom measles vaccine containing 360 micrograms Quil A/ml. The effects were compared with those caused by a sterile phosphate-buffered saline solution and by diphtheria-pertussis-tetanus-polio (DPT-polio) vaccine. Groups of six male rats were injected im with 0.25 ml of the test solution: on Day 0 in the left and on Day 7 in the right musculus gastrocnemius. On Day 14 the animals were killed, and the left and right inguinal lymph nodes were weighed. These organs and the left and right musculus gastrocnemius were investigated microscopically. The only hematological changes observed occurred in the group injected with DPT-polio vaccine: a decrease in the Hb value and in the number of erythrocytes and an increase in mean corpuscular hemoglobin content and in the number of leucocytes. The weights of the left and right inguinal lymph nodes were significantly increased in rats injected with DPT-polio vaccine, iscom measles vaccine, and the high dose of Quil A. The most intense granulomatous inflammatory reaction, mainly consisting of activated macrophages, was observed at the injection sites of all animals of the DPT-polio group. Only one animal injected with the iscom measles vaccine showed a moderate inflammatory reaction of the same type.(ABSTRACT TRUNCATED AT 250 WORDS)