An αβ T‐cell‐independent immunoprotective response towards gut coccidia is supported by γδ cells

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Abstract
Although γδ cells are commonly hypothesized to provide a ‘first line of defence’, γδ-cell-deficient mice are generally only marginally more susceptible to pathogens. Because γδ cells are enriched within epithelia, it is important to resolve whether immunoprotective capacity towards epithelial-tropic pathogens is absent from the γδ-cell compartment, or whether such activity is present but simply redundant with that of αβ T cells. In this work, following infection of the intestinal epithelium of αβ T-cell-deficient mice with the coccidian parasite, Eimeria vermiformis, γδ cells were shown to support the rapid activation of other lymphoid cells and to confer a transferable antipathogen effect that could be eradicated by neutralization of interferon-γ. However, unlike αβ T cells, these effects of γδ cells showed no evidence of functional immunological memory. These results are directly relevant to coccidiosis, an economically significant disease of livestock, and should have general relevance to infections involving αβ T-cell deficiencies, e.g. cryptosporidiosis in patients with acquired immune deficiency syndrome (AIDS).