Comparative Studies on the Physical Characteristics of the Heritable Haptoglobin Groups of Human Serum

Abstract

Ultracentrifugal studies of the α2-proteins of normal human serum before and after the addition of hemoglobin have revealed three separate and clearly distinguishable patterns based on the three major serum haptoglobin groups. Isolation of the three haptoglobin hemoglobin complexes disclosed characteristic patterns for each group. The heterozygote was found to possess electrophoretic and ultracentrifugal components not seen in either homozygote. Separation of normal human serum, to which hemoglobin had been added, by conventional starch zone electrophoresis resulted in three characteristic patterns which also permitted the ready identification of the serum haptoglobin group. The haptoglobin hemoglobin complex from Group 1-1 had the fastest mobility and that of Group 2-2 the slowest. The heterozygote Group 2-1 had an intermediate mobility. Immunologic differences between the haptoglobin hemoglobin complexes of the three groups could not be detected. Some of the variations in the reported electrophoretic and ultracentrifugal patterns of normal human serum could be reasonably ascribed to the group variation of the haptoglobins in man. The physical studies imply that the proteins characteristic of the heterozygote differ in size and charge from those present in either of the two homozygotes and indicate that the genetic control of the synthesis of the serum haptoglobins is probably exceedingly complex.

Antigenic Differences Among Human Haptoglobins

“…Absorption of the antiserum with Hp 1-1 removes all re activity with the faster Hp 2-1 component; the slower component still reacts but to a lesser degree than do the Hp 2-2 components. Data obtained with ultracentrifugal analysis (17,19) suggest that Hp 2-1 is a hybrid protein (19) differing in molecular weight from both Hp 2-2 and 1-1. The data presented here show that one com ponent of Hp 2-1 is indistinguishable from Hp 1-1, both on the basis of penetrance in the agar gel and immunologic properties.…”

“…17 It has been demonstrated with starch gel immunoelectrophoresis that Hp 2-1 is composed of at least two antigenically different components. One of these penetrates to the same degree in the gel as does Hp 1-1; the other component, which is a series of polymers, penetrates slightly farther into the gel than do the Hp 2-2 poly mers.…”

“…(15) were among the first to demonstrate that haptoglobins are good antigens. The existence of three genetically determined haptoglobins that differ in physico-chemical properties suggests that these proteins also may differ in antigenic structure, but several attempts to demonstrate such antigenic differences were unsuccessful (16,17). In these attempts weak antisera against whole human serum (16) or against haptoglobin-hemoglobin complexes (17) were used.…”

Immunogenetics of human haptoglobins

“…All common Hp types have a strong affinity for hemoglobin (Hb); the Hb binding site in Hp appears to be located on the hp,3-chain (4). Early studies on the immunologic characteristics of Hp did not reveal differences among the three phenotypes, or between free and Hb-bound Hp (5,6). Recently, however, with the use of more discriminating antiReceived for publication 2 May 1968. sera both these categories of antigenic differences have been demonstrated by Korngold (7,8) and by Eichmann, Deicher, and Cleve (9).…”

Subtyping Haptoglobins with Precipitating Antisera

“…Family studies showed that the variants are deter mined by two haptoglobin alleles, Hp1 and Hp2 [42], giving the phenotypes Hp 1-1, Hp 1-2 and Hp 2-2. Hp 1-1 behaves as a homo geneous protein in physico-chemical experiments while Hp 1-2 and Hp 2-2 behave like a series of stable polymers [2,3,13,21,29,38]. C o n n e l l , D ix o n and S m it h ie s subjected purified haptoglobin to reductive cleavage and electrophoresis in acid starch gel containing mercaptoethanol and 8 m urea [12,40,41], They showed that all three types of haptoglobin arc composed of two kinds of polypeptide chains: a and ft.…”