defining the lymphoid stress surveillance response in human skin
TRANSCRIPT
Poster Abstracts
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Defi ning the lymphoid stress surveillance response in human skinRichard Woolf, Adrian Hayday
Abstract Background The skin contains many tissue-resident immune cells increasingly acknowledged as having key roles in maintaining tissue integrity and excluding infection. In lymphoid stress surveillance, lymphocytes are activated rapidly and in synchrony by stress ligands expressed by tissue cells after cellular stress and engage activating receptors such as NKG2D. Although much of this process has been worked out in model systems, whether this capability exists in human skin is not entirely clear. Therefore, we have characterised the human skin-resident lymphocyte compartment, and measured functional responsiveness of cells to see whether certain T cells have the capacity to respond rapidly to tissue stress.
Methods We used normal adult human skin discarded after cutaneous surgery. Protocols were established to isolate and characterise lymphocytes by tissue disaggregation or three-dimensional explant culture. Skin-resident lymphocytes were characterised by multicolour fl ow cytometry, including cell-surface receptor expression and cytokine production after in-vitro stimulation.
Findings After ex-vivo isolation, distinct skin-resident lymphocyte subsets were identifi ed, including the unconventional lymphocytes, γδ T cells and natural killer (NK) cells. Subsets were consistent across individuals; expressed as a mean (SD) percentage of leucocytes isolated, there were 46·1% CD4 T cells (15·2), 20·2% CD8 T cells (14·8), 1·6% γδ T cells (1·0), and 6·2% NK cells (5·0) (n=7–10). Explant culture greatly increased lymphocyte yield, enabling detailed functional characterisation. In addition, culture conditions greatly amplifi ed the γδ T-cell compartment (1·6–4·0%, p=0·01, Student’s t test). Skin-resident lymphocytes displayed skin-homing surface markers and a memory phenotype. Lymphocytes diff ered in expression of co-stimulatory receptors, with CD8 T cells, γδ T cells, and NK cells expressing the activating receptor NKG2D. Upon in-vitro activation, skin-resident lymphocytes readily produced cytokines and displayed distinct cytokine-producing profi les, with the response dependent on the strength of T-cell receptor-mediated activation. Skin-derived NKG2D+ lymphocytes had clear potential to produce both tumour necrosis factor α and interferon γ.
Interpretation Skin-resident lymphocytes could be isolated from healthy human skin. Consistent with published data, cultured skin-resident αβ T cells maintained a tissue-resident memory (TRM) phenotype. In addition, that skin γδ T cell and NK cells also had a TRM-type phenotype was a novel fi nding. Distinct NKG2D+ lymphocytes were identifi ed, which showed variable expression of additional activatory or inhibitory co-receptors, and were functionally competent with distinct cytokine-producing subsets. This system provides a platform to further characterise human skin-resident lymphocytes and their potential to be directly activated by surrounding tissue dysregulation.
Funding UK Medical Research Council.
ContributorsRW conceived and conducted the experiments. AH conceived and supervised the work. Both authors wrote the abstract.
Confl icts of interestWe declare that we have no confl icts of interest.
Published OnlineFebruary 26, 2014
Poster 79
Peter Gorer Department of Immunobiology, King's College
London, London, UK (R Woolf MBChB,
Prof A Hayday PhD); and London Research Institute,
Cancer Research UK, London, UK (Prof A Hayday)
Correspondence to: Dr Richard Woolf, Department of
Immunobiology, 2nd Floor, Borough Wing, Guy's Campus,
London SE1 9RT, [email protected]