INTERFERON-ALPHA-8B IS THE ONLY VARIANT OF INTERFERON-ALPHA-8 IDENTIFIED IN A LARGE HUMAN-POPULATION

Three variants of human interferon (IFN)-alpha 8 gene, that is, IFN-al pha 8a, IFN-alpha 8b, and IFN-alpha 8c, have been reported previously. They differ from each other by changes in their coding region at nucl eotide positions 359-360, 372, and 550, Human genomic DNA obtained fro m over 28,000 healthy blood donors and from 4 human cell lines was use d in the polymerase chain reaction (PCR) designed for specific amplifi cation of the IFN-alpha 8 gene fragments. The resulting PCR product wa s analyzed by (1) restriction endonuclease digestion, (2) DNA sequenci ng, and (3) allele-specific secondary PCR amplification, Only one sequ ence for IFN-alpha 8 was identified, and that was for IFN-alpha 8b. Th e sequences for IFN-alpha 8a and IFN-alpha 8c were not detected after PCR amplification either in the pooled leukocytes obtained from >28,00 0 individuals or in cell lines tested. These data suggest that the nat urally occurring variant or allele for IFN-alpha 8 in the population i s IFN-alpha 8b. IFN-alpha 8a and IFN-alpha 8c variants were consistent ly below the level of detection of the assays and, if present at all i n the population, are very rare.