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The effect of post-traumatic stress syndrome on the outcome of influenza vaccination

Psychological stress is known to affect immune function and to influence on infectious disease susceptibility. Previous studies have demonstrated that chronic stress can impair humoral immune response to influenza vaccination but no data is available on post-traumatic stress disorder (PTSD). PTSD, according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), is a condition (or anxiety disorder) that can occur after exposure to extreme traumatic experience and is accompanied by intense fear, helplessness or horror. Exposure to trauma can result in immune deregulation, and increasing number of evidence suggests that there are immune alterations associated with PTSD. The aim of this study was to determine the effect of psychological stress on the immune response to influenza vaccination in war related PTSD patients (n=28). Peripheral blood mononuclear cells (PBMC) and sera were obtained before and 14 days after vaccination (Agrippal, Chiron, Italy) from patients and control subjects during 2003/2004 winter season. Detection of specific antiviral antibody titre in sera for all viral strains contained in the vaccine was performed with inhibition of hemagglutination (IH) assay. Ex vivo tetramer staining of recently activated CD8+ T lymphocytes was used for monitoring of T cell response specific for HLA-A*0201-restricted influenza A matrix antigen (M158-66) and haemaglutinin antigens (A/New Caledonia/H1N1, HA344-353, HA541-549) before and after influenza vaccination. Sixteen patients showed 4-fold increase of H1N1 antibody titre 14 days after vaccination. In four of total ten HLA-A*0201+ patients 2- to 4-fold increase of frequency of recently activated influenza-specific T cells was observed after vaccination. However, PTSD patients showed diminished frequencies of influenza-specific CD8+ T cells after vaccination compared to healthy controls. Generated humoral response in our patients argues against the hypothesis that post-traumatic stress might influence the protection following vaccination. Diminished cellular response in PTSD patients could indicate that immune dysregulation observed earlier in these patients selectively affects cellular immune response.

PTSD; vaccine; influenza; antigen-specific CD8+ T cells

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