An-Chuan Wang

Chemical differences of adult, fetal and hypogammaglobulinemic IgG immunoglobulins☆

Abstract Heavy and light chains of IgG molecules from pooled normal adult sera, pooled normal fetal sera, and pooled hypogammaglobulinemic sera were studied by means for starch gel electrophoresis in hypertonic urea. Differences were demonstrated among the heavy chain preparations. These data indicated that: 1. (1) The transfer of IgG molecules across the placenta has a selective nature. Not all species of material IgG pass equally well into the fetal circulation. IgG2 subclass immunoglobulins were detected in the fetal serum in only trace amounts. 2. (2) Neonatal IgG molecules are not entirely composed of molecules passively transferred from the mother. 3. (3) IgG molecules from hypogammaglobulinemic patients are less heterogeneous than those from normal people.

The identity of light chains of monoclonal IgG and monoclonal IgM in one patient

Abstract A patient with an IgG myeloma was found to have an elevated monoclonal IgM of the type seen in Waldenstroms macroglobulinemia. The light chains of the monoclonal IgG and monoclonal IgM were both kappa type. They were indistinguishable by urea starch gel electrophoresis, peptide mapping and amino acid analysis. Optical rotatory dispersion and circular dichroism studies showed that both light chains had similar secondary structure in saline at pH 7·3. Immunofluorescence studies indicated that the two proteins were being synthetized by different plasma cells in the bone marrow. These results provide evidence for a single kind of light polypeptide chain produced by two different clones of plasma cells.

Chemical analyses of cryoglobulins

Abstract A total of nine monoclonal cryoglobulins were subjected to chemical analyses. Results showed that they are preferentially associated with light chains with unblocked N-termini and also probably with heavy chain of VHI subgroup.

Chemical analyses of variable regions of heavy and light chains of cold agglutinins.

Abstract. The variable regions of cold agglutinins with anti‐I and anti‐Pr specificities were investigated by N‐terminal amino acid sequencing and by analyses of pyrrolidone‐carboxylic acid‐blocked peptides after digestion of polypeptide chains with Nargase. Results showed that the heavy chains of four IgM anti‐I cold agglutinins are exclusively VHI subgroups and their light chains are exclusively VKII subgroup. In contrast, the light chains of two cold agglutinins with anti‐Pr specificity are not VKII, while their heavy chains are not restricted to a single subgroup.

Genetic control of gamma chain synthesis: A chemical and evolutionary study of the Gm(a) factor of immunoglobulins

Abstract The amino acid sequences of the Gm“a” peptide, the Gm“non-a” peptide and the OWM peptide of immunoglobulins have been elucidated. The results indicate that both the a and non-a peptides in humans and higher apes were evolutionarily derived from the OWM peptide in the Old World Monkeys by single-step point mutations. One mutation which converted a glutamic acid residue on the OWM peptide into an aspartic acid residue gave rise to the a peptide; while another mutation which converted a leucine residue on the OWM peptide into a methionine residue gave rise to the non-a peptide. The single locus hypothesis versus the gene complex hypothesis concerning the biosynthesis of the genetically controlled Gm factors in humans were tested by examining the peptide maps of the IgG heavy chains of homozygous Gm (a+/a+) normal individuals. The results showed that both the a and the non-a peptides were present on such peptide maps. Therefore, these results support the hypothesis that multiple loci controlled the inheritance of the γ chains (or the constant regions of γ chains) of immunoglobulins.

GENE EXPANSION AND ANTIBODY VARIABILITY

The amino acid sequence near the N‐terminus of a human immunoglobulin (Ig) light (L) chain has been determined. This sequence is more homologous to avian Ig L chains than to human Ig L chains, and defines an additional variable (V‐) region subgroup designated as VλVI. These data also suggest that all vertebrates share large numbers of Ig V‐region genes and that species‐specific’residues reflect the expression in different species of different sets of V‐region genes. Control at a level equivalent to ‘regulatory genes’ * determines which genes are expressed. Our findings raise a question concerning the possible role of redundant DNA, in that at least some of the ‘nonsense’ DNA in one species may actually be sense’DNA in another. We hypothesize that in evolution‘gene expansion’is a regular mechanism for the generation of new genes and that different members of a given group of repetitious genes are expressed in different species. Such a phenomenon is basically similar to the‘mechanism’controlling the differential expression of genes during embryonic differentiation. Our hypothesis differs from the previous version of the germ‐line hypothesis proposed for genetic control of antibody variability which involves ‘sudden excessive gene expansion and contraction’. Evidence suggesting that the‘gene expansion’mechanism may also be applicable to a lesser degree to other gene systems is briefly reviewed and discussed.

IgA AND EVOLUTION OF IMMUNOGLOBULINS

Five classes of immunoglobulins, namely IgG, IgM, IgA, IgD and IgE, have thus far been described in human serum. IgA was first described by Williams in 1954 under the name of ‘px’. It has been designated as ‘/&A’ by Burtin et al. (1957) and ‘ylK by Heremans (1960). The name IgA (or ?A) was finally recommended by a World Health Organization committee on the nomenclature of immunoglobulins in 1964 and subsequently was accepted by most of the immunologists. In contrast to IgG, IgM, IgD and perhaps also IgE which are all present predominantly in the serum, IgA occurs as the most preponderant immunoglobulin class in exocrine secretions, such as saliva, tears and mucus from lung, nose, vagina and gastrointestinal tract (Gugler & van Muralt, 1959; Hanson, 1960; Chodirker & Tomasi, 1963; Tomasi & Zigelbaum, 1963). IgA is the major antibody involved in the defense against local non-invasive infectious diseases (Tomasi & Bienenstock, 1968; Dayton et al., 1969; Bellanti, 1971 ; Medici & Buergy, 1971; Williams & Gibbons, 1972; Gerbrandy & van Dura, 1972). The predominance of IgA in exocrine secretions makes the evolutionary study of IgA a particularly interesting subject since it may encounter some selective pressure not encountered by other immunoglobulins. Two articles (Vaerman, 1970; Grey, 1969) which have discussed this subject in detail, are strongly recommended for background information. IgA myeloma proteins with antibody activity, i.e. with defined antigen-combining specificities, have been described in man (Videbock et al., 1973) and mouse (Eisen et al., 1968; Potter, 1970). It is reasonable to assume that myeloma IgA proteins represent typical molecular species in the normal IgA pool. On this basis, chemical data on myeloma proteins have been used in order to facilitate the evolutionary comparison of different immunoglobulins existing in different animals. The terminology used herein is as close to that recommended by the World Health Organization (1964, 1966, 1968, 1969, 1973).

The Mammalian Intervertebral Disc. The Collagen of Whale Fetal Nucleus Pulposus

The hydroxyproline content and total amount of imino acids of whale nucleus collagen are in the range of variability usually observed in other mammalian collagen and about the same as the values reported for the collagen isolated from human intervertebral disc.Salt and acid extracted collagen of fetal whale nucleus pulposus was obtained with the aid of pronase. Soluble collagen preparations were also obtained without the use of pronase. Insoluble collagen was purified as gelatin. The amino acid and carbohydrate composition of these preparations was essentially the same. The salt-soluble collagen of the fetal nucleus contains 2% neutral carbohydrate, present as galactose and glucose in 1.5:1 ratio, trace amounts of hexosamine and no uronic acid. The galactose to glucose ratio is, however, higher in gelatin preparations.Carboxymethylcellulose chromatography of neutral salt-extracted collagen (after pronase) primarily showed two chromatographic components corresponding to αl and β11 chains of rat tendon solu...

The nature of ‘species-specific’ amino acid residues☆

Abstract Amino acid sequences for the first 40 N-terminal residues of three rat κ-type Bence-Jones (B.-J.) proteins and for the first 23 residues of pooled rat immunoglobulin light chains were determined. Comparison of these sequences with those of human and mouse κ chains indicates that it is difficult to find any amino acid residue which is absolutely ‘species-specific’ or ‘phylogenetically-associated’. Therefore, the ‘species-specific’ or ‘phylogenetically-associated’ residues cannot be used as a strong argument in support of either the somatic mutation or the somatic recombination hypothesis regarding the genetic control of antibody variability.

Amino acid sequences near the “switch point” of heavy chains of human immunoglobulins: Genetic hypothesis☆

Abstract We determined amino acid sequences near the juncture between the variable (V-) and the constant (C-) regions of human immunoglobulin (Ig) α, μ, γ1, γ2 and γ3 chains. Our data show that: (a) the γ1, γ2, and γ3 chains are very similar to one another at the beginning of their C-regions with approximately 90% sequence homology and (b) the α chain has more sequence homology with γ chains (57%) than with μ chains (29%) at the beginning of their C-regions, a finding in contrast to the comparison made by others at the C-termini of H-chains where α chain was found to be more homologous to μ than to γ chain. Comparison of our data with amino acid sequences of human γ1 and μ chains published to date shows that: (a) the “switch point” between the V- and C-regions of human Ig H-chains is most likely between positions 117 and 118 (Eu numbering), and (b) several residues at the end of the V-regions are either invariable or nearly invariable. A model is presented as a possible explanation for their significance in the joining of the V-and C-regions.