CPT® Code 81382

HLA Class II typing, high resolution (ie, alleles or allele groups); one locus (eg, HLA-DRB1, -DRB3/4/5, -DQB1, -DQA1, -DPB1, or -DPA1), each

The HLA Class II typing procedure, identified by CPT® Code 81382, involves high-resolution analysis of specific loci within the human leukocyte antigen (HLA) system, which is a critical component of the major histocompatibility complex (MHC). The MHC plays a vital role in the immune system by facilitating self-recognition, allowing the body to distinguish its own cells and tissues from foreign substances, including pathogens and non-self cells. HLA Class II molecules are essential for initiating immune responses and are located on the short arm of chromosome 6. This class comprises several loci, including HLA-DR, HLA-DQ, and HLA-DP, with each locus containing various alleles that define individual immune responses. Alleles are designated by the locus name followed by an asterisk (*) and a series of digits that indicate specific allele groups and variants. For example, an allele may be represented as DRB1*15, where the first two digits signify a particular group, and additional digits provide further specificity. The high-resolution typing of HLA Class II is crucial for various clinical applications, including organ transplantation, disease association studies, and understanding immune responses. The procedure typically employs molecular techniques such as polymerase chain reaction (PCR) to amplify DNA from nucleated cells, which requires prior cell lysis and protein digestion. One common method for achieving high-resolution typing is PCR sequence-specific priming (SSP), which utilizes a set of primer pairs to selectively amplify groups of alleles. This high-resolution testing is reported for each locus typed, and it is important to note that if multiple loci are analyzed, each must be reported separately. The procedure is essential for identifying specific alleles or allele groups, thereby enhancing the understanding of an individual's immune profile.