IMMUNE-RESPONSE TO INFLUENZA VACCINATION IN INSTITUTIONALIZED ELDERLY- EFFECT ON DIFFERENT T-CELL SUBSETS

Humoral and cellular immunological responses to influenza vaccination were measured in volunteers in a long-term care facility. all particip ants were vaccinated with the commercially available 1994-95 trivalent influenza vaccine and blood samples were collected before and 6 and 1 2 weeks after vaccination. Cytokine and granzyme B in peripheral blood mononuclear cell (PBMC) cultures after virus stimulation, and serum a ntibody titres were measured for each of these time points. In general , the measures of the immunological response to vaccination were low a nd variably significant. The major finding was the difference with res pect to post-vaccination measures for the two strains of influenza A c ontained in the vaccine. Geometric mean antibody titres were significa ntly higher for A/Texas/36/91 at all time points in the study when com pared to A/Shangdong/09/93. There was a corresponding rise for interle ukin-10 (IL-10) to the A/Texas/36/91 strain while no increase in IL-10 was observed in A/Shangdong/09/93-stimulated cultures after vaccinati on. In contrast, granzyme B rose after vaccination only in cultures st imulated with A/Shangdong/09/93. Interferon-gamma levels were also sig nificantly higher in these PBMC cultures. There was a poor interleukin -2 (IL-2) response to both strains of influenza A. These data suggest that different strains or subtypes of influenza A may preferentially e nhance T-helper type 1 versus type 2 responses through vaccination in institutionalized seniors. (C) 1998 Elsevier Science Ltd. All rights r eserved.