Based on the provided reference, an IgG antibody can be responsible for a specific type of chronic urticaria.
Understanding Immunoglobulins and Urticaria
Urticaria, commonly known as hives, is a skin reaction that causes itchy wheals. While various factors can trigger urticaria, immunoglobulins (antibodies) play a key role in many cases. Different types of immunoglobulins exist, each with distinct functions in the immune system.
According to the information provided, a specific immunoglobulin has been identified as a cause in a significant subset of chronic cases:
The Role of IgG in Chronic Urticaria
The reference highlights that chronic urticaria can be caused by a particular type of antibody. This antibody is described as a complement fixing, IgG antibody directed to the α-subunit of the IgE receptor.
- What does this mean? Instead of the typical IgE antibody binding to an external allergen, in this scenario, the body produces an IgG antibody that targets a component of its own cells – specifically, the receptor on mast cells and basophils where IgE normally binds. This misdirected attack is why this is considered an autoimmune mechanism.
- Prevalence: This autoimmune subgroup, where the IgG antibody targets the IgE receptor, is found in 35% to 45% of patients with chronic urticaria.
- Mechanism: When this IgG antibody binds to the IgE receptor on mast cells and basophils, it triggers the release of histamine and other chemicals, leading to the characteristic wheals and itching of urticaria.
- Identification: This autoimmune subgroup can be identified through specific tests, such as:
- An autologous skin test (where a patient's own serum is injected into their skin)
- Histamine release tests using human basophils or cutaneous mast cells
In summary, while the term "urticaria" covers various causes, the provided reference specifically implicates an IgG antibody as responsible for a significant percentage of cases within the chronic, autoimmune form of the condition.
