Friday, October 28, 2011

Topic Discussion: H1N1 vaccine in Transplantation

An interesting paper by. Katerinis et al. recently investigated the role of vaccination with the adjuvanted H1N1 vaccine in causing the production of anti – HLA antibodies in kidney transplant recipients.
This study was carried out in four cohorts of patients in Switzerland, 92 transplant recipients who had HLA antibodies checked before and 6 weeks after H1N1 vaccine, 59 transplant recipients who had been tested for HLA antibody up to 6 weeks before vaccination then again 4-8 weeks after, patients on the wait list for renal transplantation and a historical cohort from 2008 who never received the H1N1 vaccine.  In the first two cohorts 17.3% and 11.9% of patients developed anti-HLA antibodies (some donor specific while some were not) verses no patients in cohort III and 6.1% of patients in the historical cohort.  Six months after immunization the antibodies disappeared in the majority of patients.  There were two events that could have been attributed to the antibodies: one patient who developed a C4d negative thrombotic angiopathy in the kidney and another patient who developed antibody mediated rejection (however, authors report that he was non-compliant with his immunosuppression).
This is the first study in which antibody responses after H1N1 influenza vaccination led to a significant degree of HLA-antibodies.  The authors point out possible explanations including shared epitopes between influenza hemagglutinin and neuraminidase in the vaccine and HLA proteins, HLA antigens triggering a B-cell response toward the vaccine antigens, nonspecific reactions between vaccine antibodies and the antibody detection assay, and the adjuvanted vaccine triggering allosensitization by stimulating the innate immune system.
Even though there were novo HLA antibodies it is important to note that the authors do not recommend avoiding the vaccination as influenza in the transplant patients can be life threatening and the presence of these de novo antibodies were of low titer and probably not related to clinical events.  However this paper supports further studying the ability of adjuvanted vaccines in causing HLA-antibodies and possibly organ dysfunction.

Ref: I. Katerinis et al: De Novo Anti-HLA antibody after pandemic H1N1 and seasonal influenza immunization in kidney transplant recipients. Am J Transplant 2011;11:1727-1733

Post by Dr.Vinay Nair

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