Although antigens and antibodies play a large role in immunogenicity it should not be assumed that they are the only factors that do this. External factors also play a role in the immunogenicity of a vaccine.

A study was conducted to find the association between ultraviolet radiation intensity at the time of vaccination and the immune response elicited. It was concluded that the MMR vaccination in seasons of less light and subsequently less ultraviolet radiation would improve the immune response and antibody production. Similar affects were also observed after vaccination when the exposure to sunlight and ultraviolet radiation was reduced.
Ultraviolet radiation can affect immunogenicity through the modification of antigen-presenting cells(Linder et al. 2009).


How does this work?
Leukocytes are white blood cells that are involved in the body’s defence system. They take part in inflammatory and immune responses. Antigen-presenting cells (APC) are specialized leukocytes. APCs are primarily involved in engulfing and presenting fragments of an antigen so that they can be recognised by T-cells. When an antigen comes into contact with an antigen-presenting cell it is engulfed and processed.
However, ultraviolet radiation alters the antigen-presenting cells in skin so that they are presented differently (Marieb and Hoehn, 2007). In some cases the antigens are not presented on the antigen-presenting cell at all (Duthie, Kimber and Norval 1999). When an antigen presentation is incorrect, inappropriate or inefficient, it disrupts the langerhan cells (Peña-Cruz, 2010). Langerhan cell (LC) functions as antigen-presenting cells (APCs). They are said to be involved in the tolerance and resolution of cutaneous immune responses. Therefore, this may be a contributing factor for ultraviolet-mediated immunosuppression (Duthie, Kimber and Norval 1999).
The effects of different wavelengths in the ultraviolet spectrum are still not clearly understood. Currently the majority of experiments that have been carried out focus on UVB waveband as it has been regarded as the most influential in mediating immunosuppression. Uncertainty exists regarding which wavelengths within the ultraviolet spectrum contribute to immunosuppression. Due to the lack of knowledge, additional studies are required to determine whether there is really a relationship between ultraviolet induced tolerance and systemic immunosuppression. This relationship has not yet been consistently observed (Duthie, Kimber and Norval 1999).

Factors effecting immunogenicity Autoimmune disorders : Ultraviolet radiation
Immunosuppression: Adjuvants
Contributed by Sidharsha Naidoo