Haptoglobin subtyping with anti-haptoglobin alpha chain antibodies.

Specific antibodies against the human haptoglobin (HP) alpha chain were raised and used for immunoblotting after isoelectric focusing to determine Hp alpha subtypes in a reproducible and simplified manner. By eliminating the staining of the HP beta chain, HP alpha subtypes were visualized more precisely and simply than by previously reported methods. Subtypes of a total of 1211 sera, obtained from two different populations in Japan, were examined by the new method. Four HP alpha subtypes (HP 1S-1S,2FS-1S, 2FS-2FS and 2FS-2SS) and five subtypes combined with a new variant (HP 2FS-1V1, 2V1-1S, 2FS-2V1, 2FS-2V2 and 2FS-2V3) were observed. HP 1V1 belonged to HP alpha 1, and HP 2V1, 2V2 and 2V3 belonged to HP alpha 2, and their alleles were designated HP A1V1, HP A2V1, HP A2V2 and HP A2V3, respectively. The allele frequencies were calculated to be as follows: HP A1S, 0.2597; HP A1V1, 0.0004; HP A2FS, 0.7333; HP A2SS, 0.0008; HP A2V1, 0.0045; HP A2V2, 0.0008; and HP A2V3, 0.0004. The allele frequency of HP A2SS, which is common in the European population, is less frequent than HP A*2V1 in the Japanese population.