The nomenclature of properdin factor B allotypes

In a comparative study the presently known eleven allotypes of properdin factor B (Bf) were examined. Bf polymorphism consists of the two common alleles F and S, the two less common alleles F 1 and S 1 and seven further rare alleles. A variant designation has been proposed according to their relative electrophoretic mobility in comparison to the migration difference between the S and F 1 band. There rare variant alleles were redesignated: F 1.55, SO.45 and SO.7, which previously had been described as F 1.6, S 0.8 and S 1, respectively. Conversion studies did neither reveal variant mobility in the Bb nor in the Ba fragment of factor B in three of the rare alleles. This finding confirms the earlier report on one of the variants, possibly suggesting the existence of a so far unknown third clearing fragment.