Further structural and antigenic studies of light-chain amyloid proteins

Histomorphological patterns of renal amyloidosis: a correlation between histology and chemical type of amyloidosis

A retrospective study was conducted to investigate whether there was a correlation between the histological pattern of renal amyloidosis, the chemical type of amyloid protein involved and the clinical presentation. Eighteen consecutive cases of systemic amyloidosis that had renal biopsies processed and examined histopathologically at the Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur were reviewed. The age range of patients was 25 to 64 yrs (mean, 46 yrs). The male:female ratio was 2.6:1. Three patients were Malay, 9 Chinese, 3 Indian, 1 Indonesian, 1 Iban, and 1 Bisaya. According to the predominant site of amyloid deposition, 14 cases showed a glomerular pattern and 4 a vascular pattern. 8 cases were designated as 2 anti-human amyloid-A (AA) amyloidosis on the basis of permanganate-sensitivity and immunoreactivity of deposits with anti-human AA protein antibody. Ten cases contained deposits that were permanganate-resistant and nonimmunoreactive for AA protein and were designated as AL in type. The histomorphologic pattern of renal amyloidosis did not provide a reliable means of differentiating AA from AL amyloidosis. The glomerular pattern tended to present with renal manifestations such as nephrotic syndrome and chronic renal failure, whereas the vascular pattern tended to present with nonrenal manifestations such as diarrhoea. These findings may have a bearing on the pathophysiology of amyloidosis and provide clues to appropriate management.

A critical analysis of postulated pathogenetic mechanisms in amyloidogenesis

This review has examined several of the major thrusts in amyloid research, past and present. The data concerning amyloid precursor quantity, primary protein and gene structure, and precursor proteolysis have shown that there are contradictions that must be resolved before these elements can be reamalgamated into a unified view of amyloidogenesis. One possibility is presented in Figure 2. A general hypothesis of amyloid formation that accounts for the uniformity of fibril structure, amyloid staining properties, and the specific selection of precursors and their specific anatomic localization in each form of amyloid has yet to be proposed. Some of these questions may be answered by an analysis of common structural constituents in amyloid deposits. Analyzing amyloid generation in the context of these common elements separates amyloid research into several specific areas (Figure 2). The first area concerns factors that govern the expression of amyloid precursor protein genes, thus providing adequate quantities of the precursor, if such a precursor pool does not already exist. Without such a pool, amyloid deposition clearly cannot occur. The second area concerns information as to where these precursors usually bind and/or exert their normal function. Once determined, this information will likely indicate the site or sites where the particular precursor may give rise to amyloid deposits. The last area concerns factors at these local sites that govern the interaction of the precursor with basement membrane or related extracellular matrix elements that would define both the site and the final common pathway for amyloid deposition.

Partial amino acid sequence of an amyloid fibril protein from nodular primary cutaneous amyloidosis showing homology to lambda immunoglobulin light chain of variable subgroup III (a lambda III)

An amyloid fibril protein (MA) was purified as a 17,000-dalton protein from a case of nodular primary cutaneous amyloidosis, and its partial amino acid sequence (22 residues from N-terminal) was determined. A sequence closely homologous to that of the lambda III subgroup of the immunoglobulin light chain was detected. This is the third case of nodular primary cutaneous amyloidosis which has been studied at the level of sequence analysis of purified amyloid fibril proteins, and the first case of nodular primary cutaneous amyloidosis in which a lambda III amyloid protein has been shown to be present by sequence analysis.

Definition of the human immunoglobulin variable lambda (IGLV) gene subgroups

Comparison of 60 human immunoglobulin variable lambda (IGLV) sequences allowed us to define seven subgroups designated V lambda I to V lambda VII. We demonstrate that all lambda proteins sequenced so far fall into the subgroups I, II, III and VI, and that the lambda regions previously assigned to subgroups IV and V belong, in fact, to subgroups III and II, respectively. Four sequences not belonging to any of the subgroups I, II, III and VI define the new subgroups IV, V and VII. Interestingly, these subgroups show a higher homology to rabbit or mouse V lambda genes than to the other human V lambda subgroups. By comparison of the proteins either with the sequences deduced from the germ-line genes or with the consensus sequences, the rate of amino acid changes due to somatic mutations or allelic variations was evaluated in several lambda proteins. Framework and complementarity-determining regions of the human IGLV genes and proteins were delineated. Alignment of the lambda sequences shows that functional V-J rearrangement occurs, with or without deletion of nucleotides encoding one or two amino acids at the 3' end of the V gene. Diversity of the third complementarity-determining region is due to somatic mutations and to flexible V-J junction, but there is no evidence of N-diversity in the human lambda locus.

Pathological Society of Great Britain and Ireland. 154th meeting, 7-9 January 1987. Synopses of papers

The transformation of serum proteins into Congo red-sensitive fibrillar material is requisite for the onset and progression of amyloid disease. All the mechanisms which lead to the disease itself have not been elucidated, but our knowledge has increased significantly. It is apparent that in all types of amyloid fibrils, three common features are displayed by the major protein constituents. These are that the fibril protein has a serum precursor, a high degree of anti-parallel beta-sheet conformation and a distinctive ultrastructure on electron microscopy. In the AL and AA forms of amyloidosis, the putative precursors appear to undergo limited degradation to form the protein component of amyloid fibrils. It has been suggested that there may be certain primary structural characteristics inherent in precursor molecules which make them amyloidogenic, thus predisposing them to amyloid fibril formation. This would include certain subtypes of immunoglobulin light chains, possibly kappa I and lambda VI, in the AL type of amyloidosis and one of the polymorphic SAA species, SAA2, which has been identified as the predominating isotype found in AA amyloid fibrils. In AH amyloidosis, the mechanism of amyloid fibril formation appears to be simply a concentration phenomenon where elevated concentrations of B2-M are not handled normally and amyloid deposition is the result. Amyloidogenesis in the hereditary form of systemic amyloidosis may involve other factors in addition to the presence of a variant precursor prealbumin as indicated by the delayed onset of the disease. It is evident that the elucidation of the mechanism(s) which governs the onset and progression of the amyloidoses will allow future regulation and treatment of these all too often complex disorders.

Aberrant immunoglobulin synthesis in light chain amyloidosis. Free light chain and light chain fragment production by human bone marrow cells in short-term tissue culture

Bone marrow cells obtained from 14 patients with light chain amyloid (AL) deposition were examined by biosynthetic labeling techniques. These analyses identified free monoclonal light chain (L-chain) synthesis even in those patients whose serum or urine contained no M protein or free L-chains or only an intact M protein. The experiments also identified a subset of patients whose plasma cells synthesized polypeptides bearing constant region antigenic determinants that migrated more rapidly than intact L-chains on polyacrylamide gels. Since most AL fibrils contain L-chain fragments rather than intact L-chains, these studies suggested that the genesis of the fibril components may reflect aberrant synthesis, proteolytic processing, or both. We also noted that in some individuals the pattern of Ig synthesis normalized after several courses of cytotoxic therapy. Thus, we could use bone marrow Ig synthesis as a sensitive biochemical parameter for monitoring therapy. Finally, the presence of aberrant synthetic products in these clones raised questions about their origin with respect to the normal processes of transcription, translation, and posttranslational modification in Ig-producing cells.

Characterization of amyloid deposits in biopsies of 15 with "sporadic" (non-familial or plasma cell dyscrasia amyloid polyneuropathy

Review of the clinical and laboratory findings of 39 patients with amyloid polyneuropathy (AP) showed 12 cases to be hereditary and 12 to be associated with plasma cell dyscrasia (PCD). The remaining 15, termed "sporadic" AP, had neuropathy clinically indistinguishable from the other two groups but without a clinicopathologically identified PCD or positive family history. In an attempt to identify the type of amyloid in "sporadic" AP, the immunoreactivity of amyloid deposits was investigated using specific antisera raised against the following different chemical types of amyloid fibril proteins: variable regions of amyloid light chains kappa (A kappa) and lambda (A lambda), amyloid protein AA, and prealbumin. It was found that the amyloid in "sporadic" AP had A lambda antigenic determinants in ten cases, A kappa in one and prealbumin in three; in one case, the A lambda nature of amyloid was confirmed biochemically on the extracted amyloid fibrills. Thus, the most common type of AP in our population appears to be the "sporadic" form. In "sporadic" AP, the amyloid is most commonly of immunoglobulin light chain origin, even in the absence of overt PCD, and it can be rapidly categorized immunocytochemically to determine therapeutic directions or provide genetic guidance.

Isolation and characterization of a kappa amyloid fibril protein

The fibril in primary amyloidosis (AL) is composed of a monoclonal light chain or portions thereof. No unique primary structure has been identified that predisposes certain light chains to form amyloid fibrils. Currently, classification of amyloidosis is based on the biochemistry of the amyloid fibril. We determined the NH2-terminal sequence of an amyloid fibril and found it to be of the kappa I immunoglobulin subgroup. No structural alterations were detected to account for the conversion of the light-chain fragment to an amyloid fibril. Antiserum produced to the fibril protein did not react in immunodiffusion with purified LEP or MAG antigens, which are kappa I proteins. This antiserum may be directed to antigenic sites unique to the immunizing protein and is unable to recognize homologous proteins, rendering it unsuitable for immunochemical identification of amyloid deposits of light-chain origin. PAG represents the 10th reported variable kappa I amyloid fibril protein subjected to partial sequence analysis. Antisera that recognize antigenic determinants present in all members of an immunoglobulin subgroup need further development.

A second component in bovine AA amyloid fibrils not identical with protein AA is essential for AA amyloid fibrillogenesis

Amyloid fibrils were isolated from the renal papillae and glomeruli of cows with spontaneous AA amyloidosis. The fibrils were solubilized by treatment with guanidine hydrochloride (Gu HCl) and subjected to gel filtration on Sephacryl S-200. Two other fractions were obtained beside the void volume and the AA fractions. Reaggregation studies were performed by dialysing the fractions, separately or in combinations, against Gu-HCl-free solutions. Protein AA alone (about 10 kd) appeared not to precipitate. The other fractions alone and the combinations of fractions tested formed precipitates. The precipitates containing all fractions (including protein AA) or protein AA plus a fraction containing a 19- and a 23-kd protein revealed congophilic green birefringent fibrillar material. Dialysis against acidic and calcium-containing solutions gave the best results. Amyloid fibril-like material was visible on electron microscopic examination. The amino acid composition of the 19 + 23-kd material appeared to be slightly different from protein AA and evidently unlike SAP. On immunofluorescence-absorbance studies the 19 + 23-kd material appeared evidently unlike protein AA and SAP. From these findings it is concluded that for spontaneous formation of AA amyloid fibrils other non-AA proteins are necessary.

Amino acid sequences in amyloid proteins of kappa III immunoglobulin light-chain origin

The main amyloid fibril (AL) proteins extracted from the spleen of Patient So 124 with systemic amyloidosis and from a skin nodule of Patient KSA with localized amyloidosis were studied by partial amino acid sequence analysis and proved to be of kappa III immunoglobulin light-chain origin. The sequences were similar to that of Bence Jones protein V and, which has been reported to have a unique kappa III subset sequence. Thus, except for position 9 in protein AL(KSA), the amino acid sequences were identical to position 25 in AL(So 124) and in AL(KSA). The question is being raised whether this kappa III subset might contain amyloidogenic sequences.

Characterization of amyloid deposits and P component from a patient with factor X deficiency reveals proteins derived from a lambda VI light chain

Amyloid fibrils were isolated from a spleen obtained at surgery from a 58-year-old white man with primary amyloidosis presenting with factor X deficiency and responding dramatically to splenectomy. Gel filtration on Ultragel ACA 54 in 5 M guanidine 1 M acetic acid yielded components with molecular weights between 17,000 and 13,000. Two of them (17K and 15K) were studied in detail. Antigenic and amino acid sequence analysis showed that these proteins were related to lambda VI immunoglobulin light chain. The predominant protein subunits of the amyloid fibril of the deposits (17K) was processed at the carboxy terminus in the same section of the constant region as the only other lambda VI amyloid protein previously reported. Amino terminal sequence of the 15K protein revealed not only degradation at the C terminal, but also minor degradation at the amino terminal (three residues difference from the 17K species). P component was also isolated from the spleen and characterized. This represents the first antigenic and sequence analysis of tissue amyloid proteins and P component from a patient presenting with factor X deficiency and another example of amyloid proteins derived from the newly discovered amyloidogenic lambda VI light chain subgroup.

Bence Jones proteins and light chains of immunoglobulins. Preferential association of the V lambda VI subgroup of human light chains with amyloidosis AL (lambda)

An antiserum prepared against a lambda-Bence Jones protein from a patient (SUT) who had multiple myeloma and amyloidosis had specificity for lambda-light chains of the chemically defined variable (V) region lambda-chain subgroup lambda VI. Sequence analyses of protein SUT and of five other lambda-light chains recognized immunologically as of the V lambda VI subgroup revealed that all six proteins had the N-terminal sequence characteristic for prototype lambda VI proteins. The isotypic nature of the V lambda VI subgroup was demonstrated immunochemically: lambda VI molecules were detected among light chains isolated from the IgG proteins of each of 12 normal individuals and lambda VI antigenic determinants were also detectable on the intact IgG proteins. The frequency of lambda VI molecules among lambda-type light chains is estimated to be approximately 5% based on the finding that 5 of 91 lambda Bence Jones proteins were of the V lambda VI subgroup. Proteins of the V lambda VI subgroup, in contrast to those of the other five chemically-classified lambda chain subgroup, appear to be preferentially associated with the amyloid process as evidenced by the fact that all six lambda VI proteins were obtained from patients with amyloidosis AL and, in addition, 5 of 42 lambda-type monoclonal immunoglobulins from patients with primary or myeloma-associated amyloidosis were classified by immunodiffusion analyses as having lambda VI-type light chains.

Localized laryngeal amyloidosis: partial characterization of an amyloid fibril protein AL

Amyloid fibrils were extracted from a patient Wr with more than 10 yr history of localized laryngeal amyloidosis. Degraded amyloid fibrils reacted in immunodiffusion with an antiserum against an amyloid protein of immunoglobulin kappa light chain origin, showing a line of identity with a kappa I amyloid protein. The protein Wr had a blocked aminoterminal, previously only reported in lambda chains. Amino acid sequence analysis of a fragment of the protein showed it to be an immunoglobulin light chain protein of V kappa I or V kappa III subgroup. The protein had a few unusual amino acid residues as compared to other kappa light chains. The findings support the view that the fibrils in localized, tumour-like amyloidosis are composed by homogeneous immunoglobulin light chain proteins in the same way as is seen in primary and myeloma associated systemic amyloidosis. It is possible that unusual light chains are over-represented in amyloid fibrils.