Effect Of Immunosuppression On T-Helper 2 And B-Cell Responses To Influenza Vaccination

Background. Influenza vaccine immunogenicity is suboptimal in immunocompromised patients. However, there are limited data on the interplay of T-and B-cell responses to vaccination with simultaneous immunosuppression.Methods. We collected peripheral blood mononuclear cells from transplant recipients before and 1 month after seasonal influenza vaccination. Before and after vaccination, H1N1-specific T-and B-cell activation were quantified with flow cytometry. We also developed a mathematical model using T-and B-cellmarkers and mycophenolate mofetil (MMF) dosage.Results. In the 47 patients analyzed, seroconversion to H1N1 antigen was demonstrated in 34%. H1N1-specific interleukin 4 (IL-4)-producing CD4(+) T-cell frequencies increased significantly after vaccination in 53% of patients. Prevaccine expression of H1N1-induced HLA-DR and CD86 on B cells was high in patients who seroconverted. Seroconversion against H1N1 was strongly associated with HLA-DR expression on B cells, which was dependent on the increase between prevaccine and postvaccine H1N1-specific IL-4(+)CD4(+) T cells (R-2 = 0.35). High doses of MMF (>= 2 g/d) led to lower seroconversion rates, smaller increase in H1N1-specific IL-4(+)CD4(+) T cells, and reduced HLA-DR expression on B cells. The mathematical model incorporating a MMF-inhibited positive feedback loop between H1N1-specific IL-4(+)CD4(+) T cells and HLA-DR expression on B cells captured seroconversion with high specificity.Conclusions. Seroconversion is associated with influenza-specific T-helper 2 and B-cell activation and seems to be modulated by MMF.