Noa Madar-Balakirski, Uri Arad, Sharon Amir, Michal Mandelboim, Ella Mendelson, Dan Caspi and Ori Elkayam
Objective: Monitoring of immune responses is essential in the care of immunosuppressed individuals, including rheumatic patients. Evaluation of cellular immunity is essential for confirming virus-specific effector cell functions, but it is poorly standardized, and suffers from technical limitations and inaccurate results. There is, therefore, a need for reliable techniques for assessing cell-mediated immunity. In this study we compared the cell-mediated immunity response to influenza vaccine between a population of rheumatoid arthritis (RA) patients and healthy subjects by three methods.
Methods: Trivalent influenza subunit vaccine was administered to 18 RA patients who were taking disease-modifying antirheumatic drugs and to 18 healthy controls. Peripheral blood mononuclear cells (PBMCs) and sera were obtained immediately before and ~28 days after vaccination. Cell-mediated immunity responses to vaccination were evaluated by (1) flow cytometric analysis of IL-2/IFN-γ production in activated CD4/CD8 T-cells, (2) enzyme-linked immunosorbent assay for the analysis of IFN-γ secretion, and (3) Granzyme B activity assay. Humoral response was evaluated by the hemagglutination inhibition assay.
Results: Vaccination induced a significant increase in PBMC IFN-γ secretion and Granzyme B activity in the RA patients. Granzyme B activity also significantly increased in the controls, but there was no change in the levels of secreted IFN-γ. No group differences in the frequencies of IFN-γ/IL-2-producing activated CD4/CD8 T-cells were observed by flow cytometry. The geometric mean of hemagglutination inhibition antibody titers increased significantly for the H1N1/H3N2 influenza strains in both groups.
Conclusions: Granzyme B activity assay was the only method to detect a significant cell-mediated immunity response in both groups while significant increase in IFN-γ secretion was demonstrated only in RA patients. Flow cytometric analysis failed to show IL-2 and IFN-γ production in both groups. Currently available methods for measuring cellular responsiveness to influenza vaccination are inconsistent and limited in their ability to reflect acquired cellular immunity.