Scientists have found that a reduced immune response to vaccines in elderly humans and mice is associated with the fact that those weaker response to interferon, in connection with which the dendritic cells are weaker stimulate follicular T-helper cells, which in turn can not cope with the regulation of maturation of B-cells of the immune system. When scientists after vaccination swabbed the injection site with cream that stimulated the immune response and interferon production, the number specific to the vaccine T-helper cells and B-cells in older mice increased. Article published in the journal eLife.
Vaccines based on T-cells, stimulate the formation of germ centres in lymphatic nodes in these zones are divided and are selected B-cell immunity. Vaccines work in the body of children and young people, however the older a person is, the less effective will this vaccine. Disrupt germ centers may be many factors, as for the maturation of B-cells have a certain cellular microenvironment, and faults in any of its elements can hinder the process. However, the exact mechanisms of the formation of germ centres deteriorates with age, is unknown.
Follicular T-helper cells — key regulators which B-cells are ready to exit from germ center, the receptors which are not exactly fit to the antigen and which cells can cause an autoimmune reaction and should be destroyed. Maturation of this type of T-lifotsitov trigger dendritic cells, and vaccination is a major role played by myeloid dendritic cells of the second type. Impaired formation of follicular T-helper cells interfere with germ centers in old mice.
Steberg of Marisa (Marisa Stebegg) from the Institute of Babraham and her colleagues from the UK and the USA investigated the immune response to vaccination of people in two age groups: 18-36 and 65-75 years, and mice of two or three and 22-24 months from birth. Before injection and after seven and 42 days after the participants took the blood, and in mice on the day of vaccination and after 10 days examined inguinal lymph nodes using flow cytometry.
The researchers then checked what affects T-lifecity, the internal processes of the cells themselves or their surroundings. For this, follicular T-helper cells transplanted from young mice to the old Vice versa. Mice have also introduced fluorescent labeled protein antigens, to see what dendritic cells will participate in the presentation of antigen and stimulation of T-helper cells.
The contents are specific to the vaccine antibodies in the blood of older people was five times lower than in young (p = 0,0004). The number of circulating follicular T-helper cells in the older age group was also reduced after vaccination (p < 0.05), although the injection there were no differences. After 10 days, but not immediately after injection in the inguinal lymph nodes of old mice the number of B-year-olds in the germ centers and the size of the centers was reduced 10 times (p = 0, 0002). The number of antibodies and follicular T-helper cells in the blood serum of old mice was also lower than that of the young.