An HLA-DRB1 typing procedure by means of sequence-specific primer (SSP
) amplification was developed for 65 different DRB1 subtypes. Subtypin
g is achieved by the performance of two subsequent PCR assays (PCR-I a
ssay and PCR-2 assay) using a limited number of reactions. The PCR-1 a
ssay determined low-resolution HLA-DRB1 typing, i.e. the serologically
defined specificities DR1, 2, 3, 4, 11, 12, 6, 7, 8, 9 and 10. The se
cond exon of the DRB1 gene is amplified also in this PCR-1 assay. High
-resolution subtyping for positively identified alleles was performed
in the PCR-2 assay with the exon-2 product from PCR-1 assay as DNA tem
plate. PCR reactions were carried out using unpurified primers in reac
tion volumes of 20 mu l and 100 ng of chromosomal DNA. After 3 hours,
the results of the PCR-1 assay were analyzed and subsequently subtypin
g results in the PCR-2 assay were obtained in another 1.5 hours. A tot
al of 249 DNA samples was typed by this method. No false positive nor
false negative results were obtained in DRB1 typing of 32 homozygous c
ell lines, 56 serologically well-defined panel cells and 125 unrelated
individuals. Segregation of the amplification patterns was investigat
ed in 36 members of 7 two-generation families. DRB1 subtyping revealed
codominant Mendelian segregation for all subtypes investigated. In co
nclusion, LR-HR-PCR-SSP typing is a fast and reliable typing technique
for routine DNA typing purposes which gives complete DRB1 subtyping w
ithin 4.5 h. Besides low-resolution DRB typing, also high-resolution D
RB subtyping for prospective HLA-DR matching in cadaveric renal transp
lantation is possible by this method.