DISCRIMINATION OF HUMAN PLACENTAL ALKALINE-PHOSPHATASE ALLELIC VARIANTS BY MONOCLONAL-ANTIBODIES

  • 1 January 1983
    • journal article
    • research article
    • Vol. 35  (1) , 1-20
Abstract
Monoclonal antibodies (18) were produced by the mouse hydridoma method using purified placental alkaline phosphatase (ALP) as antigen. The ability of the various antibodies to discriminate among allelic variants of the enzyme was tested using a large panel of placental ALP that were typed electrophoretically. The panel included sets of samples of each of the 6 common polymorphic phenotypes as well as a series of rare variants. The reactivity of each antibody with each placental ALP (binding ratio) was determined relative to a single standard placental ALP (type 1) in a quantitative binding assay. The findings for 6 of the antibodies were already reported. The results on the other 12 antibodies are presented here, and the combined data on the total series of 18 antibodies are analyzed and discussed. Six of the 18 antibodies showed significantly reduced binding to one or another of the products of the 3 common alleles. In 3 cases, the discrimination was reflected by essentially all-or-none binding reactions. In the other 3 cases, the binding differences were less marked but could be demonstrated by quantitative comparisons of the binding ratios. Quantitative binding ratio comparisons also enabled heterozygotes to be differentiated from homozygotes in each case. Some of the antibodies showed reduced binding with certain of the rare variant ALP electrophoretic phenotypes. At a minimum, this unselected series of 18 antibodies is directed to at least 9 different antigenic determinants on the surface of the placental ALP molecule. The results illustrate the power of monoclonal antibodies to discriminate among allelic variants of enzymes.