Age-related immune system differences may affect how the body responds to influenza vaccination, reports a new study, by Dr. Ning Jenny Jiang, who is now an assistant professor in the Department of Biomedical Engineering at The University of Texas at Austin.
Ning Jenny Jiang
Age-related immune system differences may affect how the body responds to influenza vaccination, reports a new study, by Dr. Ning Jenny Jiang, who is now an assistant professor in the Department of Biomedical Engineering at The University of Texas at Austin. Findings in the paper “Lineage Structure of the Human Antibody Repertoire in Response to Influenza Vaccination,” which was published in the journal Science Translational Medicine, indicate that flu vaccines may work differently in the elderly, although it's too early to say if these differences make vaccines more or less effective.
Vaccination is like a training exercise for the body's defense army against foreign invaders. The foot soldiers in this process are a type of cell called B cells, whose weapons are a large and diverse set of molecules called antibodies. During this mock combat, B cells keep tweaking their weapons to make them more specific to the weakened or dead viruses in a vaccine. The B cells able to make the most effective antibodies create a repertoire of potential responses that can be called upon and expanded if needed.
Jiang and colleagues analyzed antibody repertoires in blood samples drawn from 17 human volunteers who were immunized with 2009 or 2010 seasonal influenza vaccines. These volunteers were recruited from three age groups: children eight to 17 years of age, young adults 18 to 30 years of age, and elderly individuals aged 70 to 100 years.
By taking advantage of high-throughput DNA sequencing technology, the researchers were able to perform a 'head count' of antibodies at the peak of volunteers' immune response to the flu vaccine. They noticed significant differences in the composition of antibodies responding to the vaccine among the various age groups. After counting the antibodies, Jiang and colleagues compared and grouped antibodies that likely evolved from the same ancestor. They found that the number of distinct antibody types in the immune system shrinks with age. In other words, older immune systems have fewer weapons to choose from.
The results suggest that flu vaccines may work differently in the elderly. However, this study does not suggest that the elderly stop getting flu shots, the authors' caution. Rather, elderly individuals should reduce any activities that may increase their exposure to influenza viruses and seek medical advice if noticing signs of early influenza infection.
The study, which Jiang conducted as a postdoctoral researcher working with Dr. Stephen Quake at Stanford University, is the first of its kind to address the important issue of how B cell clonality changes with age. Gaining a quantitative understanding of the composition of these cells is critical to other areas of medicine, including early cancer detection and immunotherapy. Jiang’s research is expanding into cancer immunology through a related T cell project, which is collaboration between her and Stanford researcher Dr. Mark Davis.
Read a reference to the study from NIH Director Francis Collins' blog.
The clone wars: Upon vaccination or antigen stimulation, our immune system goes through an intensive selection process to pick the best antibodies and massively produce them. Each cluster of dots and sticks in the figure indicates an antibody clonal lineage. Most of the lineages are made of one kind of antibody sequence. However a few lineages evolve to harbor tens of different antibody sequences, each differeing by one or a few nucleotides. These highly expanded clones are the ones most likely to have been selected by the immune system to responsd to the vaccine administered. Illustration by Ning Jenny Jiang.
