Epitope spreading

Epitope spreading is a phenomenon observed in the immune response where the antibody response and/or T cell response changes over time to target different epitopes of the same antigen. This process can occur in both autoimmune diseases and infections, and is thought to contribute to the progression and diversification of the immune response.

Overview

Epitope spreading occurs when the immune response initially targets a specific epitope, but then begins to target additional epitopes on the same antigen. This can occur as a result of molecular mimicry, where the immune system mistakenly recognizes self-antigens as foreign due to their similarity to pathogenic antigens. It can also occur as a result of antigen processing and presentation, where different epitopes of the same antigen are presented to the immune system at different times.

Mechanisms

The mechanisms underlying epitope spreading are not fully understood, but several factors are thought to contribute. These include the release of cryptic epitopes, which are normally hidden from the immune system but can be exposed during the process of antigen processing and presentation. Additionally, the cross-reactivity of antibodies and T cells, which allows them to recognize and respond to multiple epitopes, may also play a role.

Clinical significance

Epitope spreading has been implicated in the progression of several autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, and type 1 diabetes. In these diseases, the immune response initially targets a specific epitope, but then begins to target additional epitopes, leading to a broadening of the immune response and increased tissue damage.

In the context of infections, epitope spreading can contribute to the diversification of the immune response, potentially enhancing the ability of the immune system to control the infection. However, it can also lead to the development of immune escape variants, where the pathogen evolves to change its epitopes and evade the immune response.

See also

• Antigen
• Epitope
• Immune response
• Autoimmune disease
• Infection