Determination of hemoglobin Bart's in alpha thalassemia traits by two-site immunoradiometric assay. II. Detection of hemoglobin Bart's in alpha thalassemia traits.

A sensitive method for the determination of minute amounts of Hb Bart's in hemolysate of alpha thalassemia-1 and alpha thalassemia-2 was carried out by two-site immunoradiometric assay. This technique is very sensitive and is able to detect minute amounts of substances. When this method is used with specific anti-Hb Bart's derived from affinity column chromatography, then labelled with radioactive 125I, the two-site immunoradiometric assay will contain both the sensitivity and specificity for the determination of Hb Bart's. In this study, parents of fetus with Hb Bart's hydrops fetalis contained high levels of Hb Bart's 0.73-1.11 per cent (mean +/- S.D. = 0.86 +/- 0.12%). Parents of Hb H diseases had Hb Bart's in two groups. The first group contained high levels of Hb Bart's of 0.73-1.20 per cent (mean +/- S.D. = 0.88 +/- 0.14%), while the second group had levels of 0.39-0.45 per cent (mean +/- S.D. = 0.42 +/- 0.02%). Mothers of patients with Hb H disease contained Hb Bart's of 0.42 +/- 0.48 per cent (mean +/- S.D. = 0.45 +/- 0.02%). Eight out of ten normal subjects contained low levels of Hb Bart's of 0.17-0.26 per cent (mean +/- S.D. = 0.22 +/- 0.04%), while two contained high levels of Hb Bart's of 0.46 and 0.43 per cent respectively. The two-site immunoradiometric assay was able to differentiate the level of Hb Bart's among alpha thalassemia-1, alpha thalassemia-2 and normal subjects.

Determination of hemoglobin Bart's in alpha thalassemia traits by two-site immunoradiometric assay. I. Purification of hemoglobin Bart's and preparation of specific anti-Hb Bart's.

This research report describes methods for the preparation of hemolysate and the isolation and purification of hemoglobins Bart's, A, A2, E, F and H. Procedures for the preparation of anti-Hb Bart's by injecting purified Hb Bart's into rabbits is indicated in the time schedule. The rabbit antisera were evaluated by antigen-antibody reaction in agar gel. Although the antiserum reacted with Hb Bart's but not with Hb A, A2,E and H, it also cross-reacted with Hb F. After the rabbit antisera were absorbed with Hb F, the antisera were highly specific because it only reacted with Hb Bart's. The purified specific anti-Hb Bart's was labelled with radioactive 125I by chloramine-T method. After passing through Sephadex G-100 column, the 125I labelled specific anti-Hb Bart's was obtained in the first peak. This radioactive labelled anti-Hb Bart's was ready to use in the two-site immunoradiometric assay.