Solium immune responses, human

Oncospheres of many cestode species penetrate and develop into metacestodes within cysts (cysticerci, hydatid, multilocular) in the soft tissues of their rodent, ruminant or human hosts. Thus, species such as Echinococcus granulosus, E. multilocularis, Eaenia multiceps, T. ovis, E. saginata and E solium are of economic and medical importance. Such soft tissue invasion elicits a host immune response to resist the helminths. However, although some cysts may be destroyed as evidenced by involution or calcification, the host response is often too little - too late to eliminate the invaders. The susceptibility of the host to invasion is often due to successful evasive strategies... 

One parenteral cestode that is widely accepted as a model for cysticercosis caused by T. solium in humans is Taenia crassiceps, which is found as an adult in foxes and has a rodent intermediate host. Larval T. crassiceps reproduce by budding in the peritoneal cavity of mice and can be serially transferred from mouse to mouse. The immune response, which controls larval growth, relies on T cell-mediated immune mechanisms (Lopez-Briones et al., 2001) and treatments resulting in increased delayed type hypersensitivity led to greater resistance, while AB production was unaffected (Bojalil eta/., 1993). 

Although the cellular and humoral response in experimental animals tends to be relatively uniform, it must be remembered that in man (and domestic animals) the immune responses can vary enormously. This is undoubtedly related to human genetic diversity - unlike the uniform genetic background of most experimental animals. These responses have been much studied in hydatid disease and (T. solium) cysticercosis. In the latter case, the frequency of different precipitation bands in serum immuno-electrophoresis (Fig. 11.8) and of the immunoglobulin classes (Table 11.4) show great variation between patients (226). Moreover, some patients show no humoral or cellular response whatsoever (226). Similarly, there is much variation in the immune responses to hydatid disease and, again, some patients show no detectable antibody (734). 

Fig. 11.8. Diagram of the precipitation bands in immunoelectrophoresis of sera from cases of human neurocystocercosis against an antigenic extract of Taenia solium cysticerci. Note the marked variation in the percentage frequency of different bands in different samples of sera. Some patients show no detectable immune response whatsoever. (After Flisser et al., 1986.)...

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