WHOLE VIRUS INFLUENZA VACCINE ACTIVATES DENDRITIC CELLS (DC) AND STIMULATES CYTOKINE PRODUCTION BY PERIPHERAL-BLOOD MONONUCLEAR-CELLS (PBMC) WHILE SUBUNIT VACCINES SUPPORT T-CELL PROLIFERATION

Three types of trivalent influenza vaccines were analysed for their in vitro stimulatory properties on immune cells from young healthy volun teers. A whole inactivated virus (WV) vaccine, a conventional subunit (c-SU) preparation and a new virosomal subunit (v-SU) vaccine were use d. Blood-derived DC up-regulated MHC class II, CD54, CD80 and CD86 aft er exposure to WV vaccine, indicating their functional maturation, but were only moderately affected by subunit (SU) vaccines. In addition, IL-12 and tumour necrosis factor-alpha (TNF-alpha) secretion by DC wer e markedly enhanced by WV, but not by SU vaccines. The production of I L-2 and interferon-gamma (IFN-gamma) by PBMC was also strongly stimula ted by WV, but much less by SU vaccines, among which the v-SU vaccine was a better stimulator of IL-2 secretion. In contrast to WV vaccine b oth SU vaccines were powerful stimulators of PBMC proliferation. Our r esults suggest that the presence of influenza core components leads to the activation of DC and triggers the production of cytokines by PBMC . SU vaccines are in contrast excellent stimulators of T cell growth. A combination of WV and SU vaccines in immunization regimes might allo w optimal T cell priming as well as the efficient generation and maint enance of memory cells.