CPT® Code 81370

The HLA Class I and II typing, low resolution (CPT® Code 81370) is a laboratory procedure that focuses on identifying specific human leukocyte antigens (HLAs) which are critical components of the immune system. The HLA system is part of the major histocompatibility complex (MHC), which plays a vital role in the body's ability to recognize its own cells and tissues, as well as to defend against foreign invaders such as pathogens and non-self cells. HLAs are located on the short arm of chromosome 6 and are categorized into two main classes: Class I and Class II. Class I HLAs, which include the loci HLA-A, HLA-B, and HLA-C, are particularly significant for immune responses, while Class II HLAs, which encompass loci such as DRB1, DRB3, DRB4, DRB5, and DQB1, are essential for the regulation of immune responses. Each locus can have multiple variants known as alleles, which are designated by a specific nomenclature that includes the locus name followed by an asterisk and a series of digits indicating the allele's specific group and further details. The low resolution typing performed under this code identifies antigen equivalents rather than specific alleles, which is useful in various clinical contexts, including organ transplantation and disease susceptibility assessments. The procedure typically involves molecular techniques such as polymerase chain reaction (PCR) and may utilize methods like PCR sequence specific priming (SSP) to amplify groups of alleles. This test is crucial for understanding an individual's immune profile and can aid in making informed medical decisions regarding treatments and interventions.