The structure and genetics of mouse immunoglobulins: an analysis of NZB myeloma proteins and sets of BALB/c myeloma proteins binding particular haptens.
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Amino Acid Sequence↗
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Clonal nature of the immune response to phosphorylcholine (PC). V. Cross-idiotypic specificity among heavy chains of murine anti-PC antibodies and PC-binding myeloma proteins.
Seven mouse myeloma proteins with specificity for phosphorylcholine (PC) were found to share a common antigenic determinant. This group of proteins contained members which differed in genetic origin, heavy chain class, kappa-chain subgroup, individual antigenic determinants and specificity for choline analogues. The cross-idiotypic determinant, VH-PC, was antigenically similar in each of the proteins and was associated with the variable portion of the heavy chain in the region of the antibody combining site. Further studies showed that an indistinguishable determinant was present on IgM anti-PC antibodies isolated from all strains of mice tested regardless of histocompatibility or heavy chain allotype. In view of the finding that this cross-idiotypic determinant was not found on antibodies or myeloma proteins which lacked specificity for PC, the data strongly suggest that a particular heavy chain variable region has been preserved in all mouse antibodies with specificity for PC.
Animals↗
Properties of IgA myeloma proteins isolated rom sera of patients with the hyperviscosity syndrome.
Sera, purified myeloma proteins, and urinary proteins obtained from eight patients with igA multiple myeloma were studied by physical-chemical and immunochemical methods. In six patients whose serum viscosity was increased, the sedimentation constants of the principal component of myeloma proteins ranged from 9.1 to 10.2 S. In two patients with nearly normal serum viscosity, the sedimentation constants of these proteins were 6.2 and 7.2 S. IGA-albumin complexes were detected in most of the sera, but invarying amounts; no complexes of ig with amylase, secretory component, or alpha(1)-antitrypsin were observed. Studies on isolated myeloma proteins revealed that all igA proteisn from sera with increased viscosity represented true polymers, linked by disulfide bonds, rather than noncovalently associated aggregates; J chain was detecable by both alkaline-urea disc electrophoresis and immunoelectrophoresis with a monospecific anti-J chain serum. Increased serum viscosity was not related to the igA subclass, L chain type, or the carbohydrate compositions of individual igA myeloma proteins. The urine of five patients contained free light chains corresponding in type to the light chain of the particular igA myeloma protein. However, free J chain was not detected. The immunoelectrophoretic analysis for the presence of J chain in sera of myeloma patients may be used for early and simple detection of polymeric forms of myeloma proteins.
Aged↗
Structural, functional, and idiotypic characteristics of a phosphorylcholine-binding IgA myeloma protein of C57BL/ka allotype.
An IgA phosphorylcholine (PC)-binding myeloma protein with IgCH allotypic determinants different from those of BALB/c mice is characterized. The myeloma, CBPC 2, was induced in the CB-20 strain of mice which is congenic to BALB/c but differs from it by carrying the A15 allotypic determinant of C57BL/ka mice. Sequence analysis of the CBPC 2 light chain through the first hypervariable region, as well as isoelectric point analysis, show that this chain is indistinguishable from that of T15, a PC-binding myeloma protein of BALB/c origin. The heavy chains of CBPC 2 and T15 differ by only two amino acids (positions 14 and 16) through the first hypervariable region. As measured by inhibition of precipitation, both CBPC 2 and T15 have the same specificity for PC, glycerophosphorylcholine, acetylcholine, and choline. In addition, CBPC 2 possesses the binding site-associated idiotypic determinant which is present on T15. However, like normal or induced C57BL/6 anti-PC antibody, it does not possess the nonbinding site idiotypic determinant.
Amino Acid Sequence↗
Calcium binding by a myeloma protein.
We describe a patient with immunoglobulin G (IgG)-kappa myeloma and severe, long-standing, asymptomatic hypercalcemia. Serum nonprotein-bound calcium concentration was 5.2 mg/dl (normal 4.2 to 5.0 mg/dl) at a time when total serum calcium concentration was 17.8 mg/dl. The patient's myeloma protein, IgGCAB, and Fab fragments of IgGCAB migrated more anodally when agarose gel electrophoresis was performed in the absence of calcium ion than when electrophoresis was performed in the presence of calcium ion; 60 other myeloma proteins did not demonstrate such behavior. Purified IgGCAB bound 1.5 calcium ions with a single dissociation constant of 1.2 X 10(-4) M. We speculate that the rare syndrome of myeloma and high protein-bound calcium is due to binding of calcium to variable regions of the myeloma antibody molecules.
Calcium↗
k Chain variable regions from three galactan binding myeloma proteins.
A series of seven BALB/c myeloma proteins has been identified with binding specificity for antigens containing beta(1 leads to 6)-D-galactopyranosyl moieties. We have determined the primary amino acid sequence of the first 108 residues from the light chains of three of these proteins. The framework portions of the variable regions of these three light chains are identical with residue 100 at which position three different amino acids are found in the three chains. An additional interchange was found at position 106 in one of the proteins. Based on recent DNA sequence studies suggesting that the variable region ends at residue 97, these substitutions indicate the possible existance of multiple genes coding for the region beginning at residue 98 and continuing toward the carboxy terminus. A single amino acid interchange was observed in complementarity determining regions occurring in L3. This substitution (Ile-Trp) would require changes in all three codon bases to produce the respective amino acids if one were derived from the other. Two of these chains are thus indistinguishable for their first 100 amino acids and are the first pair of k chains to exhibit complete identity over their variable regions.
Amino Acid Sequence↗
Comparison of the dimensions of the combining sites of the dinitrophenyl-binding immunoglobulin A myeloma proteins MOPC 315, MOPC 460 and XRPC 25 by spin-label mapping.
The mouse immunoglobulin A myeloma proteins MOPC 315, MOPC 460 and XRPC 25 all possess dinitrophenyl (Dnp)-binding activity. Differences in specificities were shown by measuring the affinities of a variety of haptens. By using a series of Dnp-spin-labelled haptens, the dimensions of the binding sites of the three myeloma proteins were compared by the method described for protein MOPC 315 [Sutton, Gettins, Givol, Marsh, Wain-Hobson, Willan & Dwek (1977) Biochem. J.165, 177-197]. The dinitrophenyl ring is rigidly held in all three sites. The depths of the sites are all 1.1-1.2nm, but there are differences in the lateral dimensions at the entrance to the sites. For protein XRPC 25 these dimensions are 0.75nmx0.8nm, which may be compared with 0.85nmx1.1nm for protein MOPC 315 and >/=1.0nmx1.1nm for protein MOPC 460. The site in protein MOPC 460 is more symmetrical with respect to the plane of the dinitrophenyl ring than in either of the other two myeloma proteins and also allows greater penetration of solvent. In protein XRPC 25 a positively charged residue was located at the entrance to the site, similarly positioned to that reported for protein MOPC 315 [Sutton, Gettins, Givol, Marsh, Wain-Hobson, Willan & Dwek (1977) Biochem.J.165, 177-197]. All three proteins possess lanthanide-binding sites, but only in protein MOPC 315 is there antagonism between lanthanide and hapten binding. However, the effects of the diamagnetic La(III) on the electron-spin-resonance spectra of bound Dnp spin labels in both proteins MOPC 460 and XRPC 25 suggest an interaction between the two sites. Comparison of this effect with that caused by the addition of the paramagnetic Gd(III) enables the distance between the lanthanide- and hapten-binding sites to be calculated. In both proteins MOPC 460 and MOPC 315 the metal site is approx. 1.0nm from the nitroxide moiety of the spin-labelled hapten, but in protein XRPC 25 this distance is at least 2.0nm.
Antibody Specificity↗
Kinetics and equilibrium studies on autologous and heterologous recombinations of heavy and light chains of myeloma proteins.
1. The kinetics of the heterologous recombination reaction of alkylated H chains of a myeloma protein (Jo) with alkylated L chains of another myeloma protein (Ita) were studied by following changes with time in the circular dichroism at 235 nm and the results were compared with those for the autologous recombination of Jo-H chains with Jo-H chains reported previously (T. Azuma et al.(1975) J. Biochem. 77, 473-479 and the preceding paper). The heterologous reaction also followed second-order kinetics. The second-order rate constant (kapp) for heterologous recombination was about seven times smaller than that for autologous recombination at pH 5.5, while they were similar between pH 4.2 and 4.7. 2. The apparent association constants (Kapp) for the reaction, H2+L2=H2L2, were determined by measuring the ellipticities at 235 nm of mixtures of H and L chains in various ratios. The values of Kapp for the autologous and heterologous recombinations were both pH-dependent and changed from 10(6) M-1 at pH 3.9 to 108 M-1 at pH 4.3. Using these values of kapp and Kapp, the half-time for the dissociation of autologous H2L2 to H2 and L2 at pH 4.3 was estimated to be 80 hr.
Binding Sites↗
Comparisons of myeloma proteins from NZB and BALB/c mice: structural and functional differences of heavy chains.
The N-terminal sequences from heavy variable regions of 47 myeloma proteins of the NZB mouse have been analyzed. Sixteen of these VH regions have unblocked alpha amino groups and have been analyzed over their N-terminal 20 residues by automatic sequence analysis. These sequence data along with the antigen-binding profiles and immunoglobulin class distribution are compared with comparable data from BALB/c myeloma proteins. These comparisons suggest that the NZB and BALB/c populations of myeloma proteins are distinct from one another. The genetic implications of this conclusion are discussed.
Amino Acid Sequence↗
Crystallization of the Fv fragment of mouse myeloma protein M315.
The Fv fragment of mouse myeloma protein M313 was crystallized from poly(ethylene glycol) solution in the form of monoclinic crystals, space group C2 and unit cell dimensions a = 5.96 nm (59.6 A), b = 5.66 nm (56.6 A), c = 13.79 nm (13.9 A) and beta = 99.7 degrees. Some unusual effects of poly(ethylene glycol)on protein crystals were noted and are discussed.
Animals↗
Isolation of a VHClambda fragment on tryptic digestion of human IgD myeloma proteins.
The tryptic digestion pattern of IgD myeloma proteins is reported. The Fab delta of fragment is shown to be very susceptible to further degradation to yield a novel fragment composed of VH and Clambda domains which are still bound through the interchain disulphide bridge. Reduction results in a change in M.W. from ca. 26,000 to 13,000. The loss of Fd delta of isotypic determinants may be of importance to studies in which membrane bound IgD is detected or measured after release from the cell surface by enzyme digestion.
Epitopes↗
Myeloma proteins from NZB and BALB/c mice: structural and functional differences.
Structural and functional analyses of myeloma immunoglobulins from inbred BALB/c mice and humans have provided important insights into the structure of the antibody molecule and the expression and evolution of antibody genes. One important question concerning these analyses is whether the myeloma process selects, in a nonrandom manner, the lymphocytes to be transformed. The availability of myeloma tumors in a second inbred strain of mouse, NZB, permits us to approach this question. In this respect. the NH2-terminal amino acid sequences of 27 kappa light chains as well as data relating to the antigen-binding properties and immunoglobulin class distribution of NZB myeloma proteins are presented and compared with similar data from the BALB/c mouse. These studies suggest that the myeloma proteins from the BALB/c and NZB mice constitute two populations of immunoglobulins with distinct functional and structural properties. The implication of this observation are discussed.
Amino Acid Sequence↗
Comparison of the secondary structures and binding sites of C-reactive protein and the phosphorylcholine-binding murine myeloma proteins.
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Animals↗
Sequence variation among heavy chains from inulin-binding myeloma proteins.
The entire sequences of the variable region of four heavy chains from BALB/c inulin-binding myeloma proteins have been determined. Among the four proteins there are six amino acid differences, all of which occur in the framework portion of the variable region. All of the six amino acid substitutions can be explained by single base mutations at the DNA level. The pattern of diversity in these proteins is compared to a previously reported group of heavy chains from phosphorylcholine-binding myeloma proteins. Unlike the phosphorylcholine-binding proteins, which (with the exception of two that are identical) have size and sequence differences in their complementarity regions, the inulin-binding heavy chains all have identical complementarity regions with H3 being extremely short. The pattern of variation observed in the anti-inulin heavy chains appears to be most easily explained by a somatic mutation mechanism. However, because none of the substitutions occur in complementarity-determining regions, they presumably would have no selective advantage and would not alter binding specificity. These proteins have further been shown to have crossreacting antigenic determinants (idiotypes). Five of the six sequence differences observed occur at positions that are internal in the molecule and thus presumably would not account for the idiotypic differences. These results suggest that most of the observed idiotypic crossreactivities will be due to differences in the light chains of the anti-inulin proteins.
Amino Acid Sequence↗
Ligand-induced redistribution and augmentation of surface-bound myeloma protein on MOPC 315 plasmacytoma cells.
The dinitrophenyl (DNP)- and trinitrophenyl (TNP)-binding IgA(lambda2) myeloma protein M315, bound on the surface of MOPC315 mouse plasmacytoma cells, was redistributed into spots, patches, and, more rarely, into caps by TNP14-BSA and by divalent but not monovalent anti-M315 antibodies. Antiserum to the L-chain of M315 (L315) induced similar redistribution of L315 bound on the surface of variant cells that only produced L315. The spots were much larger and more brilliant when the cells were incubated with the ligands at 37 degrees C than at 4 degrees C. Redistribution of M315 also occurred on M315-producing cells in peritoneal diffusion chambers incubated in BALB/c mice producing antibodies against the M315 idiotype. The clearance of immune aggregates and the regeneration of new surface-bound M315 in diffusion chambers were much slower for MOPC315 cells than that reported for B lymphocytes. The total pool of M315 was 1.9 pg per cell (about 8 x 10(6) 7S molecules), but only an average of 6 x 10(3) [125I]TNP-BSA molecules were bound on the surface of each MOPC cell at 4 degrees C. The amount of surface-bound TNP-BSA increased eightfold when the cells were preincubated at 37 degrees C with rabbit anti-mouse IgA; at 4 degrees C the increase was only twofold. The data indicate that multivalent ligands specific for M315 induce an accumulation of M315 on the cell surface that correlates with secretion; the immediate precursors of secreted myeloma protein may be arrested in their transit through the membrane by the ligands.
Animals↗
Immune responses of BALB/c mice to the idiotype of T15 and of other myeloma proteins of BALB/c origin: implications for an immune network and antibody multispecificity.
Normal adult BALB/c mice are virtually unresponsive to the idiotype of myeloma protein T15 when immunized with purified T15. However, antibodies to the T15 idiotype can be elicited by T15 in BALB/c mice that are reared in a germ-free environment or injected as newborns with an alloantiserum to the idiotype. Some germ-free and neonatally suppressed mice also produce helper cells (presumably T helpers) that enhance B-cell production of anti-DNP antibodies in response to DNP-T15. Taken together with previous studies, the present results mean that so far there are no exceptions to the rule that BALB/c mice have B and T cells that can respond to idiotypes of myeloma proteins of BALB/c origin. There appears to be a reciprocal relation between the natural prevalence of an immunoglobulin's idiotype and its immunogenicity in isologous individuals. The findings support proposals for an immune network of idiotypes and anti-idiotypes. Besides binding one or more extrinsic antigens, it is likely that each immunoglobulin also binds the idiotype of some other immunoglobulin. An immune network therefore implies multispecificity of antibodies.
Animals↗
[Rule of antibody structure. Primary structure of a human monoclonal IgA-immunoglobulin (myeloma protein Tro). VII. Purification and characterization of the disulfide bridges].
Myeloma Protein Tro has been isolated from the plasma of a myeloma patient. Monomeric IgA was separated from its polymer (by chromatography on Sephadex G-200). Both the forms were split with pepsin or cyanogen bromide and, if necessary, with thermolysin and subtilisin. The cystin-containing peptides were isolated from the hydrolysates by chromatography on Sephadex, ion-exchange columns, preparative paper chromatography, thin-layer chromatography, electrophoresis or by a combination of these methods. They were characterized by amino acid analyses and by determination of the N-terminal amino acids using the Dansyl-Edman procedure. Thus all the disulfide bridges of an IgA1 immunoglobulin could be established. The monomer has all together 48 cysteins, seven in each L- and seventeen in each H-chain; all these are covalently bonded by SS-bridges. Free SH-groups were not detected. The J-chain could only be identified serologically in the polymeric form of the protein. It is shown that the subunits of the polymers are covalently attached through either Cysl3, Cysl7 or both these residues of the H-chain.
Amino Acid Sequence↗
[Rule of antibody structure: the primary structure of a human monoclonal IgA1-immunoglobulin (myeloma protein Tro), I. Purification and characterization of the protein and its L- and H-chains (author's transl)].
Myeloma protein Tro was prepared from the serum of a myeloma patient by ammonium sulfate precipitation. It was purified by gel filtration and ion exchange chromatography or by Pevikon block electrophoresis. The purity of the preparation was tested by several electrophoretic or immunoelectrophoretic methods. L- and H-chains of the purified protein after reduction and alkylation were separated by gel chromatography. The protein and its L- and H-chains were characterized by amino acid analyses and end-group determinations.
Amino Acid Sequence↗