PCR-based HLA class II typing.

T h e h u m a n leukocyte ant igen (HLA) class II molecules are cell-surface glycoproteins involved in the regulat ion of i m m u n e responses. Allelic variation at the HLA class lI loci is an important consideration in major areas of medicine and biology. For instance, detailed knowledge of the allelic constitution at class lI loci is required for match ing of suitable donors and recipients for bone marrow and other tissue transplantat ions. Susceptibility to a number of au to immune diseases has also been found to be associated with specific residues, alleles, or haplotypes at class II loci, (9-17) and characterizat ion of these loci provides an opportuni ty for early identif ication and initiation of immuno the rapy for individuals at risk of developing these diseases. The class II po lymorphism also provides an excellent marker system for paternity determinat ions and for purposes of individual identification in forensic medicine. 118,19) Finally, these loci are valuable tools in de termining evolut ionary relationships at the DNA level. In this review we discuss the pros and cons of the alternate methods available for genetic typing of the allelic variation at class II loci for these various applications, using the polymerase chain reaction (PCR).