Immune response to influenza vaccination in institutionalized elderly: effect on different T-cell subsets

Area of Science:

• Immunology
• Vaccinology
• Geriatric Medicine

Background:

• Assessing immune responses to influenza vaccination is crucial, especially in vulnerable populations like seniors in long-term care.
• Understanding strain-specific immune reactions can inform vaccine development and public health strategies.

Purpose of the Study:

• To evaluate humoral and cellular immunological responses to trivalent influenza vaccination in institutionalized seniors.
• To compare the immune response to the two influenza A strains included in the 1994-95 vaccine.

Main Methods:

• Volunteers in a long-term care facility received the 1994-95 trivalent influenza vaccine.
• Blood samples were collected pre-vaccination and 6 and 12 weeks post-vaccination.
• Serum antibody titres, cytokine production (IL-10, IFN-γ, IL-2), and granzyme B levels in peripheral blood mononuclear cell (PBMC) cultures were measured.

Main Results:

• Overall immune responses to vaccination were generally low and variable.
• Significantly higher antibody titres were observed for influenza A/Texas/36/91 compared to A/Shangdong/09/93.
• Interleukin-10 (IL-10) levels increased in response to A/Texas/36/91, but not A/Shangdong/09/93.
• Granzyme B and Interferon-gamma (IFN-γ) levels rose after vaccination in response to A/Shangdong/09/93 stimulation.
• A poor interleukin-2 (IL-2) response was noted for both influenza A strains.

Conclusions:

• Influenza A strains within the vaccine elicited differential immune responses in elderly individuals.
• Vaccination may preferentially stimulate T-helper type 1 (Th1) versus T-helper type 2 (Th2) responses depending on the specific influenza A strain.
• These findings highlight the complexity of immune responses to influenza vaccination in institutionalized seniors.