HLA-Cw 18

HLA-Cw*18

HLA-Cw*18 is a specific allele of the HLA-C gene, which is part of the human leukocyte antigen (HLA) system. The HLA system plays a crucial role in the immune system by helping the body distinguish between self and non-self molecules. This article provides a comprehensive overview of HLA-Cw*18, including its genetic characteristics, clinical significance, and role in transplantation and disease association.

Genetic Characteristics

HLA-Cw*18 is one of the many alleles of the HLA-C gene, located on chromosome 6 at the 6p21.3 locus. The HLA-C gene is part of the major histocompatibility complex (MHC) class I molecules, which present endogenous antigens to CD8+ T cells. The HLA-Cw*18 allele is defined by specific nucleotide sequences that result in unique amino acid sequences in the HLA-C protein.

Structure

The HLA-C molecule is composed of a heavy chain and a light chain (β2-microglobulin). The heavy chain is encoded by the HLA-C gene and consists of three extracellular domains (α1, α2, and α3), a transmembrane domain, and a cytoplasmic tail. The α1 and α2 domains form the peptide-binding groove, which is responsible for presenting peptides to T cells.

Polymorphism

HLA-Cw*18 exhibits polymorphism, which is the presence of multiple alleles at a gene locus. This polymorphism is crucial for the diversity of the immune response, allowing the immune system to recognize a wide array of pathogens. The specific polymorphic sites in HLA-Cw*18 contribute to its unique peptide-binding properties.

Clinical Significance

HLA-Cw*18, like other HLA alleles, is important in the context of organ transplantation, disease susceptibility, and immune response.

Transplantation

In organ transplantation, matching donor and recipient HLA alleles is critical to reduce the risk of graft rejection. HLA-Cw*18 typing is part of the HLA matching process, particularly in bone marrow and kidney transplants. Mismatches in HLA-C alleles can lead to increased risk of acute and chronic rejection.

Disease Association

Certain HLA alleles, including HLA-Cw*18, have been associated with susceptibility or resistance to various diseases. For example, HLA-C alleles are known to influence the progression of HIV infection and the development of autoimmune diseases such as psoriasis and ankylosing spondylitis.

Role in Immune Response

HLA-Cw*18, as part of the MHC class I molecules, presents endogenous peptides to CD8+ cytotoxic T lymphocytes. This presentation is crucial for the immune system's ability to detect and destroy infected or malignant cells. The specific peptides presented by HLA-Cw*18 can influence the effectiveness of the immune response.

Also see

• HLA-C
• Major histocompatibility complex
• HLA typing
• Organ transplantation
• Autoimmune diseases

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