The immune system is a powerful bodily system that defends against invaders at any given moment. While our first line of defense against foreign cells and viruses include barriers such as the skin and mucous membranes, more specific cells can mount a defense against pathogens that are able to slip past.
T lymphocytes are a type of cell that can respond to specific pathogens that invade the body. When inactive, these cells are referred to as ‘naive’. After activation, T lymphocytes can be differentiated into helper T cells (TH), cytotoxic T cells (TC) and memory T cells. TH and TC cells are involved in destruction of specific pathogens, while memory T cells ‘remember’ invaders for later defense. When the same pathogen is reintroduced to the immune system at a later time, memory T cells can mount a defense much quicker and more effectively than the first response to that pathogen.
Vitamin D plays an important role in the immune system. Research has found that vitamin D reduces the risk of the cold and flu and upper-respiratory tract infections. Additionally, low vitamin D levels is linked to several autoimmune disorders including lupus, multiple sclerosis, rheumatoid arthritis and more. Research has also supported that vitamin D’s effect of the immune system may be linked to T cell function and maturation through the vitamin D receptor; though, no studies have explored the role of vitamin D on this topic in children. Therefore, researchers cevaluated the relationship between vitamin D levels and T cell numbers within the first five years of life.