CPT® Code 81378

The HLA Class I and II typing, high resolution (CPT® Code 81378) is a specialized laboratory procedure that focuses on identifying specific human leukocyte antigen (HLA) alleles or allele groups. The HLA system is a critical component of the major histocompatibility complex (MHC), which plays a vital role in the immune system by facilitating self-recognition. This means that the MHC helps the body distinguish its own cells and tissues from foreign substances, including pathogens and non-self cells. The HLA molecules are located on the short arm of chromosome 6 and are essential for the normal functioning of the immune response. HLA molecules are categorized into two classes: Class I and Class II. Class I includes the most significant loci, namely HLA-A, HLA-B, and HLA-C, while Class II encompasses five loci, with HLA-DR, HLA-DQ, and HLA-DP being the most clinically relevant. Each locus can have multiple variants known as alleles, which are designated by the locus name followed by an asterisk (*) and a series of digits that provide specific information about the allele. For example, HLA-B*08:01 indicates a specific allele within the HLA-B locus. The high-resolution typing of HLA Class I and II is crucial for various medical applications, including organ transplantation, where matching donor and recipient HLA types can significantly reduce the risk of transplant rejection. Additionally, HLA typing is important in understanding susceptibility to certain diseases, including autoimmune disorders and some cancers. The procedure typically involves molecular techniques for DNA extraction, which require cell lysis and protein digestion. Polymerase chain reaction (PCR) is commonly employed to amplify specific DNA sequences, and one method used for high-resolution typing is PCR sequence-specific priming (SSP). This technique utilizes a panel of primer pairs to amplify groups of alleles, allowing for precise identification of HLA types. The CPT® Code 81378 is specifically used when high-resolution testing is conducted for the three Class I loci (HLA-A, HLA-B, and HLA-C) and the Class II locus (HLA-DRB1).