By using IgG-coated polystyrene balls and β-d-galactosidase-labelled Fab', sandwich enzyme immunoassays for human ferritin, immunoglobulin E (IgE), and thyroid-stimulating hormone (TSH) were developed, and their sensitivities were shown to be largely limited by the purity, binding efficiency, and amount of β-d-galactosidase-labelled Fab' used. (1) Their sensitivities were enhanced 10 to 50-fold by using affinity-purified Fab' labelled with β-d-galactosidase. (2) Their sensitivities depended upon the efficiency of specific binding of the labelled Fab' to antigens adsorbed on antibody IgG-coated polystyrene balls. (3) Their sensitivities were improved by using the minimal amount of labelled Fab' that gave a reliable calibration curve. Under optimal conditions the sensitivities obtained for ferritin, IgE, and TSH were 0·09 pg (0·2 amol), 0·48 pg (2·4 amol, 0·2 mIU), and 3 · 2 mμU (5 · 7 amol) per tube, respectively.
References
1.
KatoKFukuiHHamaguchiYEnzyme-linked immunoassay: Conjugation of the Fab' fragment of rabbit IgG with β-D-galactosidase from E. coli and its use for immunoassay. J Immunol1976; 116: 1554–60.
2.
YoshitakeSHamaguchiYIshikawaE.Efficient conjugation of rabbit Fab' with β-D-galactosidase from Escherichia coli. Scand J Immunol1979; 10: 81–6.
3.
KatoKHamaguchiYOkawaSEnzyme immunoassay in rapid progress. Lancet1977; i: 40.
4.
ImagawaMYoshitakeSIshikawaEHighly sensitive sandwich enzyme immunoassay of human IgE with β-D-galactosidase from Escherichia coli. Clin Chim Acta in press.
5.
EndoYNakanoJOhtakiSAn enzyme immunoassay for the measurement of thyroglobulin in human serum. Clin Chim Acta1979; 95: 325–36.
6.
AdachiHFukudaTFunahashiSSandwich enzymoimmunoassay of hepatitis B surface antigen (HBsAg). Vox Sang1978; 35: 219–23.
7.
WatanabeNNiitsuYOhtsukaSEnzyme immunoassay for human ferritin. Clin Chem1979; 25: 80–2.
8.
IshikawaEHamaguchiYImagawaMAn improved preparation of antibody-coated polystyrene beads for sandwich enzyme immunoassay. J Immunoassay1980; 1: 385–98.
9.
IshikawaEYamadaYHamaguchiYEnzyme-labelling with maleimides and its application to the immunoassay of peptide hormones. In: PalSB, ed. Enzyme labelled immunoassay of hormones and drugs.Walter de Gruyter, 1978: 43–57.
10.
LowryOHRosebroughNJFarrALProtein measurement with the Folin phenol reagent. J Biol Chem1951; 193: 265–76.
11.
CrichtonRR.Ferritin: Structure, synthesis and function. N Engl J Med1971; 284: 1413–22.
12.
BazaralMHamburgerRN.Standardization and stability of immunoglobulin E (IgE). J Allergy Clin Immunol1972; 49: 189–91.
13.
JohanssonSGOBennichH.Immunological studies of an atypical (Myeloma) immunoglobulin. Immunology1967; 13: 381–94.
14.
CondliffePG.Purification of human thyrotropin. Endocrinology1963; 72: 893–6.
15.
PierceJG.The subunits of pituitary thyrotropin—Their relationship to other glycoprotein hormones. Endocrinology1971; 89: 1331–44.
ZuyderhoudtFMJBoersWLinthorstCAn enzyme-linked immunoassay for ferritin in human serum and rat plasma and the influence of the iron in serum ferritin on serum iron measurement, during acute hepatitis. Clin Chim Acta1978; 88: 37–44.
18.
AnaokarSGarryPJStandeferJC.Solid-phase enzyme immunoassay for serum ferritin. Clin Chem1979; 25: 1426–31.
19.
FortierRLMcGrathWPTwomeySL.Enzyme-labeled immuno-sorbent assay for serum ferritin: Method evaluation and comparison with two radio-assays. Clin Chem1979; 25: 1466–9.
20.
ConradieJDMbheleBEL.Quantitation of serum ferritin by enzyme-linked immunosorbent assay (ELISA). S Afr Med J1980; 57: 282–7.
21.
LeeMBurgettMW.A solid phase enzyme immunoassay for the quantitation of serum ferritin. Clin Chim Acta1981; 112: 241–6.
22.
LinpisarnSKrackaLJKennedyJHWhiteheadTP.Sensitive sandwich enzyme immunoassay for serum ferritin on microtitre plates. Ann Clin Biochem1981; 18: 48–53.
23.
HoffmanDR.Estimation of serum IgE by an enzyme-linked immunosorbent assay (ELISA). J Allergy Clin Immunol1973; 51: 303–7.
24.
WeltmanJKFrackeltonARJrSzaroRPA galactosidase immunosorbent test for human immunoglobulin E. J Allergy Clin Immunol1976; 58: 426–31.
25.
GuesdonJLThierryRAvraméasS.Magnetic enzyme immunoassay for measuring human IgE. J Allergy Clin Immunol1978; 61: 23–7.
26.
HoshiKMizushimaYShojiYEnzyme-linked immunosorbent assay for measuring serum IgE. Experientia1980; 36: 1122.
27.
MiyaiKIshibashiKKumaharaY.Enzyme-linked immunoassay of thyrotropin. Clin Chim Acta1976; 67: 263–8.
28.
AlbertWHWKleinhammerGLinkeREnzyme immuno assays for in vitro diagnosis of thyroid function. In: PalSB, ed. Enzyme labelled immunoassay of hormones and drugs.Walter de Gruyter, 1978: 153–74.
29.
KatoNNaruseHIrieMFluorophotometric enzyme immunoassay of thyroid-stimulating hormone. Anal Biochem1979; 96: 419–25.
30.
KatoNIshiiSNaruseHEnzyme immunoassay of thyroid-stimulating hormone using dried blood samples a simple technique of screening for congenital hypothyroidism. Anal Lett1980; 13: 1555–65.
