In contrast, in Mycobacterium leprae-infected humans, T cells using the Vβ6-, Vβ12-, Vβ14- and Vβ19-encoded TCRs are overrepresented in lesions when compared to blood (50). Similarly, Vβ3, Vβ6 and Vβ7 are dominant in the lesions of 50% of patients with Leishmania braziliensis infection

(50), and the Vβ14 and Vβ24 gene families are overrepresented in lesions caused by Wuchereria bancrofti (21). These differences may be because of the divergent access of blood supply Forskolin molecular weight to lesions and the liver. Indeed, in other diseases, parallels in the Vβ expression have been detected in sites of disease pathogenesis and peripheral blood. For example, there is selective expansion of TCR Vβ6 in tonsillar and peripheral blood T cells in patients with IgA nephropathy (51), and another study (52) demonstrated identical β cell-specific CD8+ T cell clonotypes in both peripheral blood and pancreatic islets of individual non-obese diabetic mice. The ability to detect CD8+

TEM cells in the blood of mice immunized with Pbγ-spz indicates that it will be highly relevant to assess in clinical trials the peripheral blood of human volunteers immunized with attenuated sporozoites. By analysing TCR Vβ expression in blood, we were able to follow the expansion of CD8+ TEM cells in Kinase Inhibitor Library chemical structure individual mice. The expansion pattern observed after immunization did not change with challenge and remained the same for 8 weeks thereafter. In a similar

fashion, Walker et al. (53) monitored the expression of Vα8 on Ag-selected CD8+Vβ10+ cells in response to an immune-dominant epitope expressed on P815-CW3-transfected cells. While there was substantial variation among responder mice in Vα8 usage, the repertoires of individual animals remained relatively stable over long periods of time (<1 year). Analysis of C57BL/6 mice infected with influenza virus demonstrated the persistence of CD8+Vβ7+ PA-specific T cells 200 days after infection (54). In recent years, there has been renewed interest in the use of a whole parasite vaccine strategy and there are now intense efforts under way to prepare and formulate attenuated either sporozoites that could be cryopreserved and then inoculated by syringe (55). This interest is fuelled mainly by the ability of the whole parasite to successfully induce long-term protection. Although the single recombinant protein vaccine, RTS,S, induces protective immunity in nonexposed adults and children residing in malaria endemic areas, the protection is short-lived, and CD8+ T cell responses are not detected (56). However, little is known about the nature, source and long-term maintenance of CD8+ T cell memory induced by attenuated parasite vaccination. It is likely that the induction and maintenance CD8+ T cell immune response generated to a whole parasite is different than that seen in response to a single protein, such as in a subunit vaccine.