Mechanism of action: Topical immunotherapy acts by varied mechanisms of action. The most important mechanism is a decrease in CD4 to CD8 lymphocyte ratio which changes from 4:1 to 1:1 after contact immunotherapy. A decrease in the intra-bulbar CD6 lymphocytes and Langerhan cells is also noted. Happle et al, proposed the concept of ‘antigenic competition’, where an allergic reaction generates suppressor T cells that non-specifically inhibit the autoimmune reaction against a hair follicle constituent. Expression of class I and III MHC molecules, which are normally increased in areas affected by alopecia areata disappear after topical immunotherapy treatment 34 .A ‘cytokine inhibitor’ theory has also been postulated 34 .
Alopecia areata is an autoimmune disease that causes a person’s hair follicles to stop working as normal, resulting in sudden or gradual patchy hair loss . It can develop as a result of stress, exposure to toxins or after a viral or bacterial infection. There is a genetic link in one out of five cases. In up to 70% of cases the hair will grow back on its own within a year. However, in some cases it can lead to a more severe form of hair loss – alopecia totalis (no scalp hair) or alopecia universalis (complete hair loss on the scalp and body). Also, the stress of having alopecia areata can make the condition worse so it is worth considering early treatment. Below is a list of the range of treatment options and the pros and cons of each.