CPT® Code 81383

The HLA Class II typing, high resolution (CPT® Code 81383) is a specialized laboratory procedure that focuses on identifying specific alleles or allele groups within the human leukocyte antigen (HLA) system. 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 Class II molecules are particularly important as they are involved in initiating immune responses. They consist of five loci: DR, DQ, DP, DM, and DO, with DR, DQ, and DP being the most clinically significant. Each locus can have multiple variants known as alleles, which are designated by a specific naming convention that includes the locus name followed by an asterisk and a series of digits (e.g., HLA-DQB1*06:02P). The high-resolution typing of HLA Class II is crucial for various clinical applications, including organ transplantation, where matching donor and recipient HLA types can significantly impact transplant success. 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 the DNA, and one specific method used for high-resolution typing is PCR sequence-specific priming (SSP). This method utilizes a panel of primer pairs to selectively amplify groups of alleles, allowing for precise identification of specific HLA alleles or allele groups. The high-resolution typing is reported for each allele or allele group identified, providing essential information for clinical decision-making.