Florence A. Westholm

Serologic crossreactions among primate immunoglobulins

We have generated and characterized 50 murine monoclonal antibodies (mAb) specific for baboon IgG. We examined crossreactivity of these mAb to baboon IgM and immunoglobulin (Ig) of various other primates including human, chimpanzee, rhesus monkey, cynomolgus monkey, and African green monkey. Those mAB that crossreacted with human IgG were further examined using myeloma proteins for specificity to human Ig subclasses. One mAB crossreacted with all four human IgG subclasses and with human IgM. We further analyzed this reactivity utilizing Bence Jones proteins representative of various light (L) chain germline gene family products. This mAB reacted with Bence Jones proteins indicating the recognition of a kappa (k) L chain specificity associated with the kappa I, kappa III, and kappa IV subgroups, but not with kappa II. Based on the differences between kappa II germ line gene encoded L chains and the other kappa L chain subgroups, we ascribe this reactivity to six amino acids that define a discontinuous epitope.

Characterization and preliminary crystallographic data on the VL-related fragment of the human κI Bence Jones protein Wat

A “naturally occurring” human κI VL dimer, designated Wat, has been isolated and crystallized. Protein Wat consists of two non-covalently bound monomers, each having a molecular weight of ~ 11,500. The monomer subunit is composed of an entire variable region light chain (VL) domain closely homologous to that of the κI Bence Jones protein Roy (Hilschmann & Craig, 1965) as evidenced from amino acid composition, tryptic peptide map, and sequence analysis. Immunochemical studies substantiated that protein Wat is of the κ chain subgroup κI and lacks the isotypic and allotypic antigenic determinants associated with the κ constant region light chain domain. Two types of crystals of VL dimer Wat were obtained from ammonium sulfate or polyethylene glycol solutions. The type I crystals have unit cell dimensions of a = b = 82.6 A, c = 60.3 A, and the space group is hexagonal P62 or P64. The asymmetric unit consists of one VL dimer; the fractional volume of unit cell occupied by solvent is 0.51. The unit cell dimensions of the type II crystals are a = b = 1,08.3 A, c = 108.8 A; the space group is hexagonal P6122 or P6522. Three variable domains constitute the asymmetric unit of the type II crystals; the fractional value of the solvent (0.52) is compatible with the value obtained for the type I crystals.

Preliminary crystallographic data on the human λIII Bence Jones protein dimer Cle

Abstract A complete human λ Bence Jones protein dimer (Cle) has been isolated and crystallized. Protein Cle was characterized immunochemically and chemically as having a variable region amino acid sequence associated with light chains of the λ chain subgroup, λIII, and a constant region sequence characteristic of “non-Mcg” type λ chains. Bence Jones protein Cle contains two covalently bound intact monomers, each having a molecular weight of ~23,000. Crystals of Bence Jones protein Cle, obtained from ammonium sulfate solutions, diffract to 2.6 A resolution and have the orthorhombic space group P212121 with cell dimensions a = 113.0 A , b = 72.3 A , and c = 48.9 A . The asymmetric unit consists of a dimer with a molecular weight of ~ 46,000.

Crystallographic data on a complete κ-type human Bence-Jones protein☆

Abstract A complete human κ-type Bence—Jones protein (Fin) has been isolated and crystallized. Immunochemical and physicochemical characterization of protein Fin indicates that it is of the κ-chain subgroup, κII, and that it consists of two non-covalently bound intact monomers having a molecular weight of ~23,000 Crystals of Bence—Jones protein Fin obtained from ammonium sulfate solutions have the orthorhombic space group P2 1 2 1 2 1 with cell dimensions a = 132.0 A , b = 93.3 A , and c = 42.3 A . The asymmetric unit consists of a dimer of molecular weight ~46,000.