DOCK8 is essential for T‐cell survival and the maintenance of CD8+ T‐cell memory
Lambe T., Crawford G., Johnson AL., Crockford TL., Bouriez‐Jones T., Smyth AM., Pham THM., Zhang Q., Freeman AF., Cyster JG., Su HC., Cornall RJ.
AbstractDeficiency in the guanine nucleotide exchange factor dedicator of cytokinesis 8 (DOCK8) causes a human immunodeficiency syndrome associated with recurrent sinopulmonary and viral infections. We have recently identified a DOCK8‐deficient mouse strain, carrying an ethylnitrosourea‐induced splice‐site mutation that shows a failure to mature a humoral immune response due to the loss of germinal centre B cells. In this study, we turned to T‐cell immunity to investigate further the human immunodeficiency syndrome and its association with decreased peripheral CD4+ and CD8+ T cells. Characterisation of the DOCK8‐deficient mouse revealed T‐cell lymphopenia, with increased T‐cell turnover and decreased survival. Egress of mature CD4+ thymocytes was reduced with increased migration of these cells to the chemokine CXCL12. However, despite the two‐fold reduction in peripheral naïve T cells, the DOCK8‐deficient mice generated a normal primary CD8+ immune response and were able to survive acute influenza virus infection. The limiting effect of DOCK8 was in the normal survival of CD8+ memory T cells after infection. These findings help to explain why DOCK8‐deficient patients are susceptible to recurrent infections and provide new insights into how T‐cell memory is sustained.