Rose Lieberman

Genetics of Immunoglobulins in the Mouse

Publisher Summary This chapter discusses one aspect of the genetics of immunoglobulins in mice, the polymorphism of genes controlling the structure of the γA, γF, γG, and γH heavy chains. Inbred strains of mice vary in their heavy-chain immunoglobulin genotype, and it is possible in certain defined donor-recipient combinations to prepare precipitating antisera. These homologous antisera identify genetically controlled allotypic (antigenic) determinants that distinguish among mice with different heavy-chain immunoglobulin genotypes. Pure forms of immunoglobulins can be obtained in the form of myeloma immunoglobulins that are produced by plasma cell tumors, and plasma cell tumors can be easily induced in the highly inbred BALB/c strain of mice. These tumors can be propagated by serial transplantation in syngeneic hosts. The genes controlling the determinants on the BALB/c γA, γ G, and γH papain Fc fragments are closely linked. This cluster of genes comprises the heavy-chain linkage group. The chemical identification of immunoglobulins is based upon the analysis of the polypeptide chains of a large variety of myeloma proteins. Initially, myeloma proteins of mice were classified by heterologous rabbit antisera and, then further characterized by tryptic peptide maps of the heavy chains or the papain Fc fragments.

Genetics of IgCH (Allotype) Locus in the Mouse

The mouse is particularly useful in studies of the immunogenetics of immunoglobulins because of the availability of (1) many inbred strains [60], (2) many allotype congenic strains that genetically resemble the parental strains except for selected allotype genes [40], (3) strains in which genes regulating VH structural expression have been identified that are linked or not linked to the IgCH allotype [4, 12, 38, 39, 41, 42], (4) allotype recombinant strains in which crossing over of VH and CH genes has occurred [38, 57], (5) strains in which plasmacytomas producing homogeneous immunoglobulins can be experimentally induced [50], (6) strains in which the major histocompatibility locus (H-2) has been well characterized [30], and finally, (7) strains in which specific Ir and Ia genes have been identified [30]°

CHAPTER 4 – Immunoglobulin Allotypes

Publisher Summary The heterogeneity of immunoglobulins of a single vertebrate species is because of the fact that there are a number of genes in the germ line that dictate the structure, or control the expression, of different immunoglobulin polypeptide chains. Genetic polymorphisms of many of these genes have been discovered by serologic and chemical methods. The genetic markers on different portions of various polypeptide chains of the immunoglobulins have provided powerful tools for the study of the genetic basis of antibody structure. The allotypes of human immunoglobulins were discovered during an investigation into the anti-immunoglobulins that were present in sera of patients with hypogammaglobulinemia. The modern era of investigation of rabbit allotypes began with the discovery of isoprecipitins in the sera of rabbits injected with specific precipitates formed between antiserum of a second rabbit and corresponding antigen. Since these initial discoveries, investigations of allotypes have contributed to the understanding of immunoglobulin structure and genetics and to the concepts of the complexities of cellular interactions in development, immunity, and specific immune responses. This chapter reviews the knowledge of the genetically different forms of immunoglobulins in man, mouse, and rabbit.

Direct and indirect suppression induced by anti-idiotype antibody in the inulin-bacterial levan antigenic system

Abstract Our findings on the suppression of anti-inulin [ β (2 → 1) fructosan] antibody synthesis by anti-idiotype antibodies are reviewed in this communication. Treatment with anti-idiotype antibodies leads to suppression of those B cells which can secrete antibodies bearing that idiotype ( direct suppression ). This suppression was achieved in three models: maternally induced, pretreatment of 1-day old BALB/c mice with anti-idiotype antibody and similar treatment of adult BALB/c mice. Maternally and neonatally induced suppression was more profound and longer than suppression in adults. The direct suppression appears to be largely independent of T cell influence. In addition, we report a new phenomenon ( indirect suppression ), which is the inhibition by anti-E109 idiotype antibody of an E109 − antibody response, to antigenic determinants borne on the same carrier molecule as the β (2 → 1 ) fructosan determinant. Indirect suppression provides an important model for probing aspects of the regulation of clonal expression through idiotype specific molecules.

Isoantibodies specific for myeloma γG and γH immunoglobulins of BALB/c mice

Strain LP mice immunized with BALB/c γG myeloma immunoglobulins made precipitating antibodies that identified allotypic specificities common to all BALB/c γG immunoglobulins which were located on the papain Fc fragments, and also identified unique specificities found only on the immunizing myeloma protein. Precipitating antibodies with BALB/c γH myeloma proteins were prepared in strain AL mice. These antisera identified allotypic specificities on all γH immunoglobulins of BALB/c which were located on the papain Fc fragment. Additional specificities which differentiated the group of BALB/c γH myeloma immunoglobulins from BALB/c normal γH immunoglobulins were also found. No precipitating antibodies were found in BALB/c mice immunized with any of the γG or γH myeloma proteins. The Fc papain fragments from myeloma proteins within a class (i.e. γG or γH) gave similar tryptic peptide maps. Thus antisera identifying specificities on the Fc fragments distinguish genetic differences between mouse strains. Tryptic peptide maps of Fc fragments of γG and γH myeloma proteins differed by many peptides. A composite tryptic peptide map of a γG and a γH Fc fragment, however, showed 12 common peptides indicating large areas of common amino acid sequence. This suggests that one of the closely linked structural heavy-chain genes arose from the other by duplication.

Close linkage in genes controlling γA and γG heavy chain structure in BALB/c mice

Isoprecipitins to a myeloma γA (Adj. PC-6A) immunoglobulin, of BALB/c mice prepared in A/He, AL and NH inbred strains of mice identified allotypic specificities (determinants) on the heavy polypeptide chains of the γA myeloma immunoglobulin, specifically the Fc fragment. The anti-myeloma γA antisera are specific for the myeloma γA class of immunoglobulins and distinguish among normal yA immunoglobulins in inbred strains of mice. Four allotypic specificities (determinants), A(12), A(13), A(14) and A(−), were found among 38 inbred strains. Isoantisera specific separately for determinants (13) on the γA and (7) on the γG heavy chains of BALB/c mice were used in genetic tests to test the sera of 758 backcross progeny of a cross of (C57BL/6 × BALB/c)F 1 and C57BL/6 mice for precipitation. Sera of 366 of the same progeny showed neither the A(13) nor the G(7) determinants, whereas sera of 392 of the same progeny showed both the A(13) and G(7) determinants, indicating very close linkage in their genetic control. Thus far no recombinants have been found. Tryptic peptide maps of the γA and γG heavy chains and their Fc fragments differ by many peptides, indicating control by different structural genes.

LINKAGE IN CONTROL OF ALLOTYPIC SPECIFICITIES ON TWO DIFFERENT GAMMA-G-IMMUNOGLOBULINS.

Allotypic specificities were identified on two different myeloma proteins and the corresponding normal γG-immunoglobulins of BALB/c mice. When the sera of F2 progeny from a cross between BALB/c mice having the a1 allotype and AL mice having the a4 allotype were tested for these specificities, it was found that the two allotypic specificities of the BALB/c mice were either both present (87 mice) or both absent (36 mice), an indication of linkage in their genetic control.

How many class II immune response genes? A reappraisal of the evidence

1 Transplantation Biology Section, Clinical Research Centre, Watford Road, Harrow, Middlesex HA1 3U J, United Kingdom 2 National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892 3 Biological Research Centre, Hungarian Academy of Sciences, P. O, Box 521, H6701 Szeged, Hungary 4 National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892

Two Murine γ-Globulin Allotypic Specificities Identified by Ascitic Fluid Isoprecipitins and Determined by Allelic Genes

Conclusions 1. Two murine γ-globulin allotypic specificities, Asa1 and Asa2 were identified by ascitic fluid isoprecipitins using agar gel immunochemical methods. 2. Only one allotypic specificity, either Asa1 or Asa2, was found in each of 42 inbred strains and substrains of mice. 3. The Asa1 and Asa2 allotypic specificities are inherited by codominant autosomal alleles which are not closely linked with the brown-black locus (linkage group VIII) and the dilute-dense locus (linkage group II). 4. Substrain STR/N has the Asa 1 allele whereas STR/1N has the Asa 2 allele indicating the second known gene difference between these two substrains.

IgA polymorphism in mice: NZB and BALB/c mice produce two forms of IgA☆

There are two different forms of mouse IgA immunoglobulins, one in which light chains are disulfide-linked to each other (IgAL-L) and the second where light chains are linked to heavy chains (IgAH-L). IgA myeloma proteins from BALB/c mice are IgAL-L and those from NZB are IgAH-L. To determine whether these two forms of IgA represent allotypic or isotypic variants, we purified serum IgA and prepared IgA-secreting somatic cell hybrids from mitogen-stimulated BALB/c and NZB mice and determined the pattern of light chain linkage. It was found that each strain produces both forms of IgA and that both forms share the allotypic determinants characteristic of the mouse strain.