Delayed rejection of singleHymenolepis diminutain primary infections of young mice

Abstract

In CFLP male tapeworm-free mice, from 2 to 7 weeks old at infection, at least 80% of single Hymenolepis diminuta establish and grow but then are rejected; day of rejection defined as the first day when ≦ 50% of the worms were recovered. Young mice, 2 to 4 weeks old, usually reject their worms during days 16–20 while older mice, 5 to 7 weeks old, reject them during days 12–14. Biomass (total dry weight of all worms recovered on a given day from a group of mice) varied markedly with host age and was consistently greatest in 4-week-old mice. The position of the worm in the intestine did not vary with host age. The quality of mice (categorized by the Medical Research Council Laboratory Animals Centre) did not appear to affect the course of a primary, single H. diminuta infection although, undoubtedly, the mice had varied immunological histories. Variations in time of rejection and biomass of worms recovered are accounted for by both immunological and physiological mechanisms.

Secondary infections of Hymenolepis diminuta in mice: effects of varying worm burdens in primary and secondary infections

“…Laboratory Animal Centre graded the CFLP 4 star but the NIH had never been graded. The maintenance and infection of mice was described previously (Befus & Featherston, 1974). If large worms were not immediately obvious at autopsy, 10 cm sections of intestine were examined carefully using the procedure of Hopkins et al (1972 a) to reveal small worms which otherwise could be overlooked easily.…”

“…In primary infections the worms grow, generally exceeding 0-1 mg dry weight by days 8 or 9, but by day 10 destrobilation commences (Hopkins et al 1972a). Therefore, herein all worms < 0-1 mg on day 10 or thereafter of a primary infection are considered destrobilated; prior to this such small worms are considered to have have grown slowly (Befus & Featherston, 1974). This arbitrary definition of destrobilated worms in primary infections cannot be used for secondary worms which grow slowly, if at all (see below), and are difficult to distinguish morphologically from destrobilated worms from primary infections.…”

“…Whether considerable growth, destrobilation or expulsion of worms occurs in secondary infections was not determined. Befus & Featherston (1974) showed that the mechanism of destrobilation and expulsion in single worm primary H. diminuta infections is partially deficient in young, immunologically immature mice.…”

Immunity to tapeworms: acquired resistance toHymenolepis citelliin the mouse

“…During worm recovery, if fewer worms were recovered than the number of cysts given orally, sections of the intestine were incubated separately for one to two hours at 37°C in Hanks' saline to reveal very stunted/destrobilated worms <0-2 mg in weight. In this paper, worms <0-2 mg are considered stunted/destrobilated (BEFUS & FEATHERSTON, 1974) and when these are recovered, their numbers are represented as indicated in the legends to the figures. Worms grow more slowly in secondary infections and the problem of searching for these small worms is thus more difficult.…”

In vitrotapeworm extract-induced proliferative responses of gut-associated lymphoid cells fromHymenolepis diminutainfected mice

“…First, fewer worms become established in immune mice given a challenge infection (HOPKINS et al, 1972a;BEFUS, 1975) and rejection may be more rapid in challenged immune mice (HOPKINS et al, 1972a). Also, rejection is delayed in young mice given single H. diminuta as a primary infection (BEFUS & FEATHERSTON, 1974) and is blocked by immunosuppressive treatment of the host (HOPKINS et al, 1972b). Finally, rejection does not occur in T celldeficient (nude) mice (ISAAK et al, 1975;BLAND, 1976).…”