Immunotherapy is the treatment of disease by activating or suppressing the immune system.
- Topical immunotherapy is the induction and periodic elicitation of allergic contact dermatitis (ACD) by applying a potent contact allergen.
- Intra-lesional immunotherapy involves injecting the allergens into the skin lesion.
- Desensitisation immunotherapy where we expose patients to larger and larger amounts of allergens in an attempt to change the immune system’s response.
- In dermatology we use immunotherapy to treat alopecia areata, viral warts and skin allergies
Topical Immunotherapy in alopecia areata
A potent contact allergen is applied to the hair loss area to elicit an allergic contact dermatitis and this is repeated at regular intervals. The 2 allergens used are squaric acid dibutylester(SADBE) and diphencyprone (DPCP) and both are equally effective
- The scalp is the usual sensitization site
- A cotton tipped applicator saturated with 2% DPCP or SADBE is applied to a small area(2 cm) Patients are advised against washing the area and protect it from sunlight for 48 hours
- The following week, a low concentration is applied Applications of the contact allergen are repeated weekly with increasing concentrations to induce a mild contact eczema, with concentration adjusted according to the response
- An eczematous response (which may occur after 5 days or more) indicates that sensitization has taken place.
- Initial regrowth may be seen at 12-24 weeks. A lag period of 3 months is common between onset of treatment and presence of regrowth.
- Once cosmetically acceptable regrowth is achieved, the treatment can be tapered gradually.
- Patients may relapse if treatment is discontinued and maintenance treatment is needed
- If no regrowth was observed after 24 months there is no benefit continuing treatment
- Side-effects are few and include persistent dermatitis, painful enlarged lymph nodes in the neck, blisters and urticarial reactions
Intralesional immunotherapy in recalcitrant viral warts
The measles-mumps-rubella (MMR) vaccine has been used to treat recalcitrant warts with some success
- MMR vaccine is injected into single lesion or the largest wart in the case of multiple lesions at 2-week intervals until complete clearance or for a maximum of five treatments.
Immunotherapy in skin allergy
Immunotherapy in skin allergy is also known as desensitisation or hyposensitisation and involves exposing patients to larger and larger amounts of allergens in an attempt to change the immune system’s response. This can be done by the oral route, the sublingual route, the subcutaneous route, or the transdermal route.