Antibodies from aged individuals arise from cross-reactive memory B cells generated early in life, with reduced adaptation to recent influenza virus strains, said researchers.

‘The detrimental effect of aging on the immune system is thought to be a major cause of illness and death in elderly adults by increasing susceptibility to bacterial, fungal, and viral infections.’

The great majority of influenza deaths occur within populations older than 65 years, and aged individuals have a significantly reduced antibody response to influenza vaccination. As a result, influenza is a leading cause of death in the elderly, and the vaccine protects only a fraction of this population. 




To understand the underlying mechanisms, Wilson and his team compared how B cells and antibodies from elderly and younger adults respond to vaccination with different flu strains. While B cells from younger subjects showed a continued recent accumulation of mutations, the elderly appeared to have an essentially fixed B-cell repertoire, lacking recent adaptations that would allow the evolution of B cells to divergent influenza virus strains.
Moreover, antibodies from the elderly are less potent and less capable of protecting against the flu virus. The antibodies of elderly subjects target only conserved proteins and structures of the influenza virus, with fewer mutations that would enable effective responses against evolving viral strains. By contrast, antibodies from younger individuals are better able to recognize recently mutated molecules on the flu virus.
The findings suggest that antibodies from aged individuals arise from cross-reactive memory B cells generated early in life, with reduced adaptation to recent influenza virus strains. For example, 47% of antibodies generated from the elderly individuals bound to six or more strains of the flu virus compared to only 12% for the young adults. In addition, antibodies from the elderly individuals had higher affinity to historical strains that were circulating during their childhood and lower affinity to more contemporary strains.
Despite these observations, vaccination remains the best way to protect elderly individuals from influenza virus infection. "We are not saying that people shouldn't be vaccinated or that the current vaccines are useless for elderly individuals," says first author Carole Henry of the University of Chicago.
Advertisement
Source-Eurekalert