A study of the delayed type hypersensitivity response to varicella zoster virus antigen to investigate defects in cutaneous immunity in the elderly

• Main Author: Sandhu, D. R.
• Published: University College London (University of London) 2014
• Subjects: 616
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.626541

Immunity declines with ageing resulting in an increase in incidence and severity of infections such as shingles. We used the delayed type hypersensitivity response as a model for a memory T cell response to investigate differences in the response to VZV antigen administered into the skin between old and young individuals. We found that there is a reduced clinical response, which is associated with a lack of T cell accumulation in the old subjects. The earliest differences between the two groups include reduced activation of dermal endothelium and a reduced infiltration of CD11c+ dendritic cells in the skin of the old individuals after VZV antigen injection. This may reflect a defect in the ability of VZV specific T cells and / or innate immune cells resident in the skin to condition the cutaneous environment adequately to induce an effective adaptive immune response. There is an increased level of Tregs in the normal skin of old individuals and these Tregs may suppress the activation of skin resident cells, thereby reducing early recruitment of memory T cells from the circulation as part of the immune response. Without adequate recruitment and activation of a few VZV specific T cells, we propose there is failure to produce additional mediators needed to amplify the memory response.