CELLULAR TRANSFER OF IMMUNITY TO TRICHOSTRONG YLUS COLUBRIFORMIS IN AN ISOGENIC STRAIN OF GUINEA-PIG .2. RELATIVE SUSCEPTIBILITY OF LARVAL AND ADULT STAGES OF PARASITE TO IMMUNOLOGICAL ATTACK

Abstract

Cells obtained from mesenteric lymph nodes of highly inbred guinea pigs (Heston strain) resistant to Trichostrongylus colubriformis were injected into virgin animals of the same genotype. The adoptively immunized recipients were challenged with 1000T colubriformis larvae 4 days after transfer and slaughtered at intervals which corresponds to critical times in the development of the parasite. Differential worm counts carried out on specimens of intestine showed that a sharp decline in the number of parasites occurred between days 7 and 9. This period corresponds to the time required for the parasite to develop to the 4th larval stage. Variation of the time interval between cell transfer and challenge showed that immune cells transferred on the day of challenge and on days 4, 6 and 8 after challenge inhibited the development of infection to patency, while cells injected on day 10 were without effect. This observation confirmed that the 4th larval stage of the parasite is uniquely susceptible to the immunological attack initiated by the transferred cells and showed that these cells are effective within 24-48 hrs. after injection. This latter finding excludes the possibility of active participation in the response by the recipient. Resistance can be transferred by spleen cells and by cells obtained from lymph nodes other than the mesenteric nodes which drain the site of infection. However, the local nodes are more effective and resistance was regularly transferred with as few as 10 x 106 cells injected intravenously.