Faculty Bibliography

Light chain deposition disease (LCDD) and light chain amyloidosis (AL) are disorders of monoclonal immunoglobulin deposition in which normally soluble serum precursors form insoluble deposits in tissues. A common feature in both is the clonal proliferation of B-cells that produce pathogenic light chains. However, the deposits in LCDD differ from those in AL in that they are ultrastructurally granular rather than fibrillar and do not bind Congo red or colocalize with amyloid P component or apolipoprotein E. The reason(s) for their differences are unknown but are likely multifactorial and related to their protein conformation and their interaction with other molecules and tissue factors in the microenvironment. Knowledge of the primary structure of the light chains in LCDD is very limited. In the present study two new kappa(1) light chains from patients with LCDD are described and compared to seven other reported kappa-LCDD proteins. The N-terminal amino acid sequences of light chain GLA extracted from the renal biopsy and light chain CHO from myocardial tissue were each identical to the respective light chains isolated from the urines and to the V-region amino acid sequences translated from the cloned cDNAs obtained from bone marrow cells. The germline V-region sequences, determined from the genomic DNA in both and in MCM, a previously reported kappa(1) LCDD light chain, were identical and related to the L12a germline gene. The expressed light chains in all three exhibit amino acid substitutions that arise from somatic mutation and result in increased hydrophobicity with the potential for protein destabilization and disordered conformation

The invasive stages of the parasitic trematode Fasciola hepatica release proteinases into the medium in which they are maintained. In this study, we investigated the interaction of F. hepatica excretory/secretory (E/S) products and 2 cysteine proteinases (CL1 and CL2) purified from these products with extracellular matrix and basement membrane macromolecules. Fasciola hepatica E/S products contained collagenolytic activity on fibrillar types I and III collagen as well as basement membrane type IV collagen. CL1 and CL2 were capable of degrading acid-soluble type III and type IV collagen but not insoluble type I collagen. In contrast, neither the E/S products nor the purified CL1 and CL2 showed elastinolytic activity. Fibronectin and laminin were degraded by E/S products and by CL1 and CL2. Sequence analysis of fibronectin degradation products showed that the fragments obtained corresponded to complete biologically active domains. These results indicate that the cysteine proteinases secreted by F. hepatica may be involved in the process of tissue invasion by the parasite

Cardiomyopathy due to monoclonal light chain deposits is a complication of plasma cell disorders. The deposits may be either fibrillar as in light chain amyloid or nonfibrillar as in light chain deposition disease. The reasons for these structural differences are still unknown. We characterized the myocardial deposits by immunohistochemical examination of sections and extraction and biochemical analysis of the tissue deposits in a patient (MCM) who died of myeloma and systemic light chain deposition disease. Amino acid sequence analysis of the extracted nonfibrillar MCM kappa-light chain reveals that it belongs to the L12a germline subset of the kappa(I) protein and contains five distinctive amino acid substitutions (three in the framework region III and two in the complementarity-determining region III) that have not been reported previously in the same positions in other kappa(I) light chains. The theoretically determined isoelectric point (pI 8.21) of the MCM light chain is high compared with the low isoelectric point of other Bence Jones proteins from subjects without light chain deposition disease. The diffuse binding to basement membranes and the high isoelectric point of the MCM kappa-light chain suggest electrostatic interaction as a possible mechanism of tissue deposition. The spatial locations of the five distinctive residues and a sixth rare substitution of the MCM protein modeled on the backbone structure of REI, a kappa(I)-soluble Bence Jones light chain of known three-dimensional structure, may be responsible for protein destabilization, partial unfolding, and aggregation leading to tissue deposition

The complete amino acid sequence of the Fab fragment of protein KAU, a human monoclonal cold agglutinin (IgMk) with anti-I activity, was determined. The light chain (L-chain) consists of 215 residues; the variable (V)L region belongs to the Hum/Kv325/kIIIb sub-subgroup that is preferentially selected in human IgM autoimmune response. The joining (J) region is encoded by the Jk4 gene, and the constant region (C)L domain expresses the km3 allotypic marker. The Fd fragment contains 232 amino acids, and 120 of them comprise the variable domain. The VH region corresponds to the VHIV subgroup and is closely related to the VHIV 2.1 gene isolated from genomic DNA expressed in peripheral blood of a healthy Caucasian. The complementary-determining region 1 has a unique amino acid (Asp) at position 31, and the complementary-determining region 3 codified by the diversity segment (D) gene, shows poor homology with other known D sequences. The joining segment with two unusual substitutions at the D-J junction is encoded by the JH4 gene. Thus, cold agglutinin KAU is an IgM, VkIIIb-Jk4-km3; VHIV-JH4-C mu

The BLA cross-idiotype (XId) is present on a unique subset of rheumatoid factors (RF) that cross-react with DNA-histone. In this study, prototype Bla monoclonal RF was shown from serologic investigations and N-terminal amino acid sequence analysis to have distinct kappa chains related to the V kappa III subgroup and VH4 heavy chains. The amino terminus of the heavy chain was cyclized, rendering the protein resistant to Edman degradation and providing a possible investigator bias to the published Ig sequence data to date. This appears to be the first definitive report of a serum IgM that expresses the VH4 gene. RF with DNA cross-reactivity have been reported to be produced by human and mouse cloned cells that have the VH4 or homologous mouse Vh36-60 gene

We have determined the V region amino acid sequence and/or serologic markers (kIIIb, PSL2, and PSL3) of 24 IgM monoclonal autoantibodies with specificities of anti-gamma-globulin (RF), anti-I (cold agglutinin), anti-low density lipoprotein and anti-intermediate filaments. The data emphasize the overwhelming selection of the HumKv325/VkIIIb L chain for this family of autoantibodies. The few amino acid substitutions found within the VL regions were mainly concentrated in the complementarity-determining region 1. JK and CK genes did not show the same pattern of restriction. There is a good correlation between the amino acid sequence and the presence of the kIIIb marker. The idiotypic marker PSL2 was present in 34 out of 35 kIIIb L chains analyzed (97%) and the PSL3 in 27 (80%). Moreover, the hydrophilicity and antigenic profiles of these L chains corroborate the presence of the epitopes detected by the anti-CRI. These results demonstrate a restricted selection of the Vk genes used by a family of self reacting proteins, and an unusual evolutionary conservation of the idiotypic structure that may be involved in the network regulation

Using a panel of antibodies specific for H and L chain variable region subgroups, a panel of human monoclonal cold agglutinin (CA) and rheumatoid factor (RF) autoantibodies were analyzed. The vast majority of the two types of autoantibodies utilized VkIII L chains, many of which probably derive from the Humkv325 gene. However, while most RFs (77%) utilized VHI H chains, all the CAs used VHII subgroup H chains. These results are consistent with a model of autoantibody generation, wherein binding specificity is H chain defined in a set of antibodies that use a multipotential L chain

Rheumatoid factors (RFs) in humans have been studied intensively because of their association with autoimmune and lymphoproliferative diseases. Many human IgM-RFs express cross-reactive idiotypes (CRIs) and have homologous light chains, some of which are encoded by a single V kappa gene, termed V kappa 325. However, although antibody activity generally requires the interaction between heavy and light chain variable regions, much less is known about structural relationships among RF heavy chains. To delineate further the structural and genetic basis of RF autoantibody synthesis, we generated 'sequence-dependent' reagents specific for the human heavy and kappa light chain subgroups, and used them to analyze a panel of 27 monoclonal RFs. In addition, these proteins were tested for the expression of a heavy chain-associated CRI (G6), and a light chain-associated CRI (17.109). The results showed that most 17.109-reactive RFs contain heavy chains of the VHI subgroup, which bear the G6 idiotypic marker. However, among the 14 17.109-reactive RFs, two have heavy chains of the VHII subgroup, and another two contain heavy chains of the VHIII subgroup. Previously, we have shown that 17.109 is a phenotypic marker of the human V kappa 325 gene. Accordingly, these results demonstrate that the same human V kappa gene can combine with several VH genes from different VH gene subgroups to generate RF activity

Two electrophoretically homogeneous immunoglobulins were detected in the serum of a patient with multiple myeloma. The heavy chains were of different classes (gamma 1 and gamma 2). The light chains of both were kappa, but had different electrophoretic mobilities on polyacrylamide gels. Amino acid sequence analysis, carbohydrate determinations, and biosynthetic experiments indicated that the difference seen in their electrophoretic mobility was due to the glycosylation of one but not the other kappa-chain. The primary structure of both chains demonstrated that they both used a V kappa 1 and a J kappa 2 gene segment and the same C kappa allele, Km(1,2), and that both contained the same junctional three amino acid deletion. However, they varied by 19 amino acids in the first 94 amino terminal residues encoded for by the V kappa gene, with some of the substitutions requiring two base changes in the appropriate codons. Moreover, the malignant 'clones' producing the two proteins differed in their responses to chemotherapy. These data indicate that, although the two clones producing the serum proteins were different at the time of study, they may have arisen from the same precursor clone