The structure of Nijmegen-breakage syndrome protein 1

Interleukin 7 enhances immune response

19 May 2009

NIMR scientists have revealed an unexpected role for the cytokine interleukin 7, a T lymphocyte survival factor, in facilitating cell-cell interactions in the immune system.

Interleukin-7 (IL7) is an 'immune hormone' (or cytokine) that is vital for controlling the size and composition of the immune system. It plays an essential role in the production of both T and B lymphocytes, and is necessary for the survival of existing T lymphocytes. IL7 is responsible for promoting memory after immune responses that is the basis for vaccination. It acts by promoting cell survival but also influences the growth and metabolism of lymphocytes. IL7 treatment has recently undergone phase II clinical trials in HIV patients receiving combination antiretroviral therapy (c-ART) in order to improve T lymphocyte numbers, as levels remain low in many of these patients.

Benedict Seddon (pictured) and colleagues from NIMR's Division of Immune Cell Biology investigated how IL7 affected immune responses to influenza A virus and found that the cytokine greatly enhanced the triggering of immune responses by T lymphocytes to the virus. Surprisingly, the role of IL7 did not depend on its well documented survival properties but rather invoked a mechanism involving improved interactions with dendritic cells presenting viral antigens.

The effects of IL7 on the survival properties of T lymphocytes and their metabolism are well known. However we did not expect to find that it had a role in enhancing immune reactivity by improving T cell interactions with antigen presenting dentritic cells. This is particularly pertinent to ongoing human trials of IL7 treatment of HIV patients on c-ART, as it suggests that IL7 may be beneficial to restoring a healthy immune system in these patients by means other than simply promoting T cell production and longevity.

Dr Seddon

Original article

The research findings are published in full in:

Manoj Saini, Claire Pearson, and Benedict Seddon. (2009)  

Regulation of T cell-dendritic cell interactions by IL7 governs T cell activation and homeostasis   

Blood Epub ahead of print. Publisher abstract

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