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Heterogeneity of Human Alpha‐fetoprotein (HAFP) as Revealed by Agarose Gel Electrophoresis and Iso‐electric Focusing in Ureaacrylamide Gels
Author(s) -
LESTER E. P.,
MILLER J. B.,
YACHNIN S.
Publication year - 1978
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1978.tb03941.x
Subject(s) - isoelectric focusing , agarose , microbiology and biotechnology , isoelectric point , electrophoresis , potency , gel electrophoresis , agarose gel electrophoresis , molecular mass , polyacrylamide gel electrophoresis , chemistry , biology , chromatography , immunoelectrophoresis , sialic acid , biochemistry , in vitro , antibody , immunology , gene , enzyme
HAFP was purified from five patients with hepatoma, one with gastric cancer, and one with an embryonal cell tumor, as well as from fetal liver and a monkey tumor cell line grown in tissue culture. The pattern of microheterogeneity of purified HAFP was defined for each HAFP isolate, and was demonstrated to be present in native sera, using crossed immunoelectrophoresis in agarose gels and isoelectric focusing in polyacrylamide gels containing 8 M urea. Three, and in one case four, species were seen in agarose, and were further resolved to reveal 6 major species with isoelectric focusing which could be correlated with the agarose gel variants. We have demonstrated a relationship between the immunosuppressive potency of certain HAFP preparations and the proportion of specific HAFP isomers which they contain as shown by these techniques. We have desialylated each of our preparations and demonstrated that this does not alter immunosuppressive potency but leaves residual complex microheterogeneity. Desialylated HAFP isolates contain six major HAFP isomers by isoelectric focusing, indicating that HAFP heterogeneity is based upon multiple charge differences in the HAFP molecule, apart from sialic acid content. The nature of these charge differences remains to be determined. We postulate that these charge differences modulate the immunosuppressive potency of HAFP.