Antigenicity of A₂ Hæmoglobin

Abstract

THE heterogeneity of adult human hæmoglobin is a well-established fact^1–3. The present work was designed to determine if the slow electrophoretic fraction A₂ has antigenic specificity and if this fraction can be detected immunologically in cord blood and in the presence of hæmoglobin S and C. Previously described⁴ techniques were used for the preparation and the agar-gel electrophoresis of the hæmolysates. Following electrophoresis the agar gel was cut into sections containing the hæmoglobin fractions to be tested for antigenicity. These sections were then frozen, thawed and filtered through fritted Büchner funnels of medium porosity. The short duration (90 min.) and the use of large glass plates as the base of the agar gel made it possible to obtain quantities of eluates sufficient for immunization of rabbits. Eluates of the following fractions were used for this purpose: the main component (A₁) of normal blood and of blood from a patient with thalassæmia minor; the respective A₂ fraction and the non-hæmoglobin fraction which we have previously⁴ designated ‘unidentified component 1’ and which probably is identical with Derrien's X ₁ fraction². In addition the most cathodic part of the fœtal hæmoglobin from cord blood (Fig. 1b, area between brackets) was eluted from agar gel because of the possibility that this part contains A₂ hæmoglobin. Each eluate containing approximately 3 mgm. of protein was combined with an equal volume of Freund's adjuvant and injected into adult male albino rabbits on three or four different sites.