The mysterious immunoglobulin light chain.

The immunoglobulin light chain is mysterious from different points of view. In an evolutionary perspective there seems to be at least three major pathways but it is today impossible to say which of them is the most ancient one and which isotype belongs to which branch. It is also difficult to assess the contribution of the light chain to the binding capacity of the antibodies. It is possible that it differs from antibody to antibody but the fact that there are antibodies in camels and sharks without any light chain suggests that it is perhaps not necessary for good antigen binding.     

Immunohistochemical study of immunoglobulin light chain amyloidosis with antibodies to the immunoglobulin light chain variable region

To detect immunoglobulin (Ig) light chain amyloidosis (AL amyloidosis) in formalin-fixed, paraffin-embedded tissue sections by immunohistochemistry, polyclonal antibodies were generated against synthetic peptides corresponding to amino acids 1-19 of the Ig lambda light chain V lambda VI subgroup (anti-V lambda VI (1-19)) and the Ig kappa light chain Vkappa I subgroup (anti-Vkappa I (1-19)). Anti-V lambda VI (1-19) antibody reacted with amyloid deposits in 21 of 22 Alambda amyloidosis cases, and anti-Vkappa I (1-19) antibody reacted with amyloid deposits in 10 of 11 Akappa amyloidosis cases. Immunoreactivity varied in intensity by case and within specimens. Surprisingly, amyloid deposits were positive for anti-V kappa I (1-19) staining in one case of Alambda amyloidosis. Analysis of anti-V lambda VI (1-19) and anti-Vkappa I (1-19) antibody reactivity by ELISA showed some cross-reactivity with peptides other than antigen peptides. The antibodies were not reactive in all cases of AL amyloidosis examined but may be useful, together with anti-Ig constant region antibodies, for immunohistochemical diagnosis of AL amyloidosis.     

Sequence analysis of porcine immunoglobulin light chain cDNAs.

A porcine cDNA library was constructed using poly(A)+ RNA isolated from the spleen of an adult Minnesota miniature swine. Screening the library with antisera specific for porcine immunoglobulin light chains resulted in the selection and isolation of two recombinant clones, PLC18 and PLC3, which encode for kappa and lambda light chains, respectively. These cDNAs contain sequence information for a portion of the variable region and all of the constant region. The lengths of the constant regions are 105 amino acids for lambda and 108 amino acids for kappa. The deduced amino acid sequences of porcine immunoglobulin light chains share a high degree of homology with similar sequences from other species in both the fourth framework region and the constant region.     

Structural peculiarities of a truncated VκIII immunoglobulin light chain in myeloma with light chain deposition disease

We report on the primary sequence of the monoclonal immunoglobulin light chain (LC) REV involved in myeloma-associated light chain deposition disease (LCDD). This sequence was deduced from that of the corresponding complementary (c)DNA in bone marrow plasma cells. Products of three independent amplifications by polymerase chain reaction (PCR) were sequenced and found to be identical. The κ mRNA encoding this N-glycosylated LC showed an overall normal structure consisting of a Vκ_III segment rearranged to Jκ_II. Direct N-terminal amino acid sequencing of the circulating monoclonal IgA2,κ showed identity with the bone marrow-derived sequence. The κ-chain presented several unusual features affecting both the leader sequence and the variable (V) region. Four unique amino acid substitutions were found at positions -8, -3, -2 and -1 in the leader sequence and probably resulted in an unusual cleavage by signal peptidase, thus making the LC truncated by one residue and accounting for its unique hydrophobic N-terminus: Ile-Ile-Leu. Additional peculiarities were observed in the V region, including a Thr74 → Asn substitution creating a N-glycosylation site, and Thr53 → Ile, which was only reported once among human κIII chains, in another LCDD case, and may be of special significance at a position usually harbouring a polar amino acid.     

Mapping of the duplicated rabbit immunoglobulin kappa light chain locus.

The rabbit has two isotypic forms of the immunoglobulin kappa light chain, K1 and K2, which probably arose by duplication. In the normal rabbit, only traces of K2 light chains are produced. However, K2 levels are elevated in allotype-suppressed rabbits and in the Basilea strain which does not produce K1 because of a K1 mRNA splice site mutation. Previous cloning and sequencing showed that each isotype has its own set of J kappa genes but it was not known whether the two isotypes utilize shared or separate sets of V kappa genes. In addition, although genetic linkage of allotypes associated with the K1 and K2 genes has been demonstrated, physical linkage had not been previously demonstrated by overlapping cosmid or phage clones. We used pulsed field and transverse alternating field electrophoresis to obtain megabase maps and to estimate the size of the duplication of the rabbit kappa light chain locus. We found that the two C kappa genes are about 1 megabase apart. One explanation for the poor expression of K2, could be great physical distance from V kappa genes. However, we found that there are V kappa, J kappa and C kappa 2 genes within a approximately 105-kb fragment. Thus, physical distance of V kappa from C kappa 2 may not be the basis for poor K2 expression.     

Phylogeny of immunoglobulin structure and function. XIV. Peptide map and amino acid composition studies of shark antibody light chains

Light chains from antibodies to the streptococcal A-variant carbohydrate from individual nurse sharks were compared by peptide maps of tryptic digests and amino acid compositions. Although the amino acid compositions of the different chains were quite similar, considerable differences as well as similarities were demonstrable on peptide maps. The peptide maps were interpreted as indicating that shark L chains likely have constant and variable regions as seen in the immunoglobulins of higher animals. Furthermore the unique peptides characteristic of different L chains support the hypothesis that nurse sharks, as a species, possess a relatively large number of different L chain amino acid sequences which are compatible with antibody binding sites to the streptococcal antigen. Hence the repetoire of nurse shark antibody combining sites to this antigen appears to be quite extensive.     

The immunoglobulin light chain in poikilothermic vertebrates

Summary: The immunoglobulin light chains are classified as κ or δ in mammals and birds (homoeothermic vertebrates), but the traditional criteria for this classification are not applicable to the light chains found in poikilothermic vertebrates. Still it is possible to find some relationships between Ig light chain sequences in these animals and in those of the homoeothermic animals. It is generally accepted that the Ig light chains contribute to the antigen binding capacity of antibodies and the variability is approximately similar in all studied vertebrate species except the elasmobranchs. This might be explained by the organisation of the Ig light chain locus in these animals and the fact that the variable and joining DNA segments are joined in the genome. These conclusions are limited by the small number of species studied in this respect.     

Richter's syndrome with different immunoglobulin light chain types. Molecular and cytogenetic features indicate a common clonal origin.

To investigate the issue of clonality in Richter's syndrome, phenotypic, molecular genetic, and cytogenetic studies were performed on tumor tissue from a patient with concurrent chronic lymphocytic leukemia and diffuse large cell lymphoma in a single lymph node specimen. The tumor was biphenotypic for immunoglobulin (Ig) expression with surface Ig lambda-positive chronic lymphocytic leukemia and surface and cytoplasmic Ig kappa-positive diffuse large cell lymphoma. DNA samples prepared from areas of the lymph node rich in chronic lymphocytic leukemia cells and diffuse large cell lymphoma cells were examined in parallel. Identical Ig heavy chain gene rearrangements were detected in the BamHI and EcoRI digests of the two samples, but the patterns of rearrangement were different in the HindIII and PstI digests. Because it is very unlikely that multiple rearranged Ig heavy chain gene fragments of identical size would be found in more than one enzyme digest from two independently derived B-cell clones, it is probable that the two processes originated from a single clone. Modifications after rearrangement probably accounted for the differing band sizes seen in the HindIII and PstI digests. These conclusions are supported by cytogenetic analysis, which revealed two clones with a common primary abnormality (trisomy 12), one of which also exhibited secondary abnormalities. Therefore, Richter's syndrome may represent a composite tumor of common clonal origin, even when differences in light chain expression are identified.     

Immunogold quantitation of immunoglobulin light chains in renal amyloidosis and kappa light chain nephropathy.

By quantitative immunoelectron microscopy using protein A-gold, the authors compared the content and distribution of immunoglobulin light chain (LC) antigens in glomeruli from 11 cases of renal amyloidosis with that in two cases of kappa LC glomerulopathy and two cases of diabetic glomerulosclerosis. In a supplementary study and using a similar immunogold technique, the authors identified amyloid A in deparaffinized renal tissue from three of the 11 cases of renal amyloidosis. Each patient had similar clinical manifestations (chronic renal failure with proteinuria) and similar glomerular morphology (thickened glomerular basement membranes and nodular expansion of the mesangium). In 12 cases (10 amyloid, 2 kappa LC), immunoelectron microscopy localized LC antigens over the glomerular deposits and allowed indirect tissue quantitation of each LC antigen to the various cellular and interstitial compartments. In 6 of the 11 cases of renal amyloidosis, the amyloid labeled only for lambda, and in one, only for kappa. In one patient with Waldenström''s macroglobulinemia, who had a biclonal gammopathy, both LC were identified in the amyloid. In two cases, both of whom had a history of chronic suppurative lung disease, both LC antigens as well as amyloid A were localized to the amyloid fibrils. In only one case, in which glomerular amyloid labeled for amyloid A, the amyloid did not label for either LC. Whereas lambda LC-derived fibrils often appeared as spicules in the glomerular subepithelial space, other amyloid deposits usually accumulated in the subendothelial zone and did not form spicules. The epimembranous location of spicules suggested that the amyloid precursor protein transformed into amyloid fibrils after filtration into the urinary space. Presence of epimembranous spicules may explain the more severe proteinuric renal failure and the more rapid progression to glomerulosclerosis described in primary amyloidosis.     

Useful polyclonal antibodies against synthetic peptides corresponding to immunoglobulin light chain constant region for immunohistochemical detection of immunoglobulin light chain amyloidosis

For the immunohistochemical detection of immunoglobulin (Ig) light chain amyloidosis on formalin-fixed, paraffin-embedded tissue sections, we prepared polyclonal antibodies against synthetic peptides corresponding to positions 118-134 of Ig lambda light chain and positions 116-133 of Ig kappa light chain. Nineteen cases of systemic Ig lambda light chain amyloidosis (Alambda amyloidosis), 10 cases of systemic Ig kappa light chain amyloidosis (Akappa amyloidosis), one case of immunohistochemically unclassified systemic amyloidosis and five cases of localized Alambda amyloidosis were tested with these antibodies. Anti-lambda (118-134) antiserum and the affinity-purified antibody both reacted with 18 of the 19 cases of systemic Alambda amyloidosis and all cases of localized Alambda amyloidosis, although the immunoexpression was somewhat variable in intensity in different areas within the same specimen in both systemic and localized amyloidosis. The signal intensities in plasma cells and serum reacted for anti-lambda (118-134) antiserum were weaker than signals obtained with commercially available anti-Ig lambda light chain antibodies. Anti-kappa (116-133) antiserum and the affinity-purified antibody reacted with nine of the 10 cases of systemic Akappa amyloidosis. We conclude that these antibodies against synthetic peptides corresponding to the Ig light chain constant region are useful for the classification of amyloidosis on formalin-fixed, paraffin-embedded tissue sections.     

Chronic myopathy due to immunoglobulin light chain amyloidosis

Amyloid myopathy associated with a plasma cell dyscrasia is a rare cause of muscle hypertrophy. It can be a challenging diagnosis, since pathological findings are often elusive. In addition, the mechanism by which immunoglobulin light-chain deposition stimulates muscle overgrowth remains poorly understood. We present a 53-year old female with a 10-year history of progressive generalized muscle overgrowth. Congo-red staining and immunohistochemistry revealed perivascular lambda light chain amyloid deposits, apparent only in a second muscle biopsy. The numbers of central nuclei and satellite cells were increased, suggesting enhanced muscle progenitor cell formation. Despite the chronicity of the light chain disease, the patient showed complete resolution of hematologic findings and significant improvement of her muscle symptoms following autologous bone marrow transplantation. This case highlights the importance of early diagnosis and therapy for this treatable cause of a chronic myopathy with muscle hypertrophy.     

Nodular glomerulopathy associated with nonamyloidotic kappa light chain deposits and excess immunoglobulin light chain synthesis

A nodular glomerulopathy characterized by mesangial deposits of monoclonal kappa light chains was detected by immunofluorescence in a renal biopsy from a patient with proteinuria and hypertension. These nodules lacked the tinctorial and morphologic features of amyloid. Ultrastructurally, the nodules contained electron-dense granular deposits as well as fibrils in parallel arrangement. The fibrils measured 110-140 A in diameter. They were consistent in size with amyloid fibrils. However, they differed in lacking the randomly oriented network of typical amyloid fibrils and more closely resembled fibrils intrinsic to mesangial matrix. The patient had no bone marrow or X-ray evidence of myeloma and no evidence of free monoclonal light chains in serum or concentrated urines. Biosynthetic studies of the patient's bone marrow cells demonstrated unbalanced immunoglobulin synthesis with excess production of monoclonal kappa light chains. These observations suggest that the observed glomerulopathy results from direct deposition of monoclonal light chains. Deposits with kappa light chain determinants have been found in 7 other patients with similar nodular glomerulopathies, 4 of whom had diagnosed clinical myeloma. The lesion of nonamyloidotic nodular glomerulopathy previously described in 19 patients, nor examined by immunopathologic techniques or not shown to contain light chain determinants, may have a similar pathogenesis.     

Similar binding properties of peptide ligands for a human immunoglobulin and its light chain dimer

The urinary light chain dimer and serum monoclonal IgG1 protein from a patient (Mcg) with multiple myeloma and amyloidosis were systematically tested for their binding activities to peptides presented on solid supports. The system was validated using a series of enkephalins, beta-casomorphins and DNP-lysine derivatives which were known to complex with the dimer. Sets of peptide ligands binding to the proteins were constructed by incremental additions of amino acid residues to minimal binding units [Geysen et al., J. Immun. Meth. 102, 259-274 (1987)]. Both the amino acid sequences and the combinations of optical isomers were optimized at each stage of the syntheses. Binding could be demonstrated for ligands ranging in size from a tethered single amino acid to pentapeptides. At the dipeptide levels, the dimer and the IgG1 protein showed different preferences (Hp versus qf, where lower case letters designate D-amino acid residues). However, in a tetrapeptide ligand (qfHp) for the dimer, both of these initial preferences had converged. With few exceptions, the IgG1 molecule showed binding activity for the ligands developed for the dimer. Two sets of selected peptides, one based on Hp and the other on mW, were synthesized for diffusion into crystals of the dimer. X-ray analyses showed that these peptides bound exclusively in the main binding cavity between the "variable" domains of the dimer. As predicted from the ELISA results with tethered ligands, the relative occupancies in the crystals followed the order of tetrapeptide greater than tripeptide much greater than dipeptide. The crystallographic studies confirmed that peptides with very different sequences can bind in the same cavity.     

Immunodiagnostic capabilities of anti-free immunoglobulin light chain monoclonal antibodies

Overproduction of plasma cell-derived monoclonal free kappa or lambda immunoglobulin light chains (FLCs) is a hallmark of multiple myeloma, AL amyloidosis, and light chain deposition disease. Because these components serve as unique cellular and serologic biomarkers, their detection and quantitation has diagnostic, therapeutic, and prognostic import. In this regard, we have developed monoclonal antibodies (mAbs) that specifically recognize the kappa or lambda FLC products of all known human variable and constant region light chain genes. We now report the results of our studies that have demonstrated the capability of these reagents to measure, in a modified fluid-phase capture enzyme-linked immunosorbent assay (ELISA), serum kappa and lambda FLCs at concentrations as low as 5 and 15 ng/mL, respectively. The mAb-based ELISA has greater sensitivity and reproducibility than does the commercially available immunoturbidimetric assay that uses polyclonal anti-FLC antibodies. In addition, the mAbs can immunostain monoclonal FLC-producing plasma cells and pathologic light chain-related amyloid and nonfibrillar tissue deposits. Our anti-FLC mAbs, with their high degree of reactivity and versatility, may provide an invaluable tool in the diagnosis and management of light chain-associated disease.     

Free immunoglobulin light chain synthesis by neoplastic cells in leukaemic reticuloendotheliosis.

Neoplastic cell preparations from four patients with clinically and morphologically well-defined leukaemic reticuloendotheliosis (LRE) were investigated for their capacity to synthesize immunoglobulin in vitro. Neoplastic cells from all cases synthesized immunoglobulin of the same light chain class as expressed at their cell surface. Labelled IgM and IgD were identified in cell lysates while free light chain was the predominant labelled immunoglobulin product in the LRE culture supernatants. The capacity of LRE cells to synthesize immunoglobulin and free light chain was similar to that of neoplastic cells from patients with chronic lymphocytic leukaemia, and provides further evidence for the B-lymphocyte origin of the neoplastic cells in LRE.     

Free immunoglobulin light chain synthesis by lymphocytes from patients with hypogammaglobulinaemia.

Lymphocytes from six individuals with reduced or deficient serum immunoglobulins of one or more class were assessed for immunoglobulin production in vitro. There was no clinical evidence of a secondary cause for hypogammaglobulinaemia and three of the cases were receiving immunoglobulin therapy. The predominant immunoglobulin product in the culture supernatants form four cases was free light chain. In contrast, peripheral lymphocytes from two cases with partial IgA deficiency and from normal individuals exhibited a balanced synthesis of heavy and light chains. These findings are discussed with particular reference to free light chain synthesis by immature neoplastic B lymphocytes and to normal B lymphocyte differentiation.     

Single light chain subclass (kappa chain) immunoglobulin deposition in glomerulonephritis

Renal glomerular disease characterized by the deposition of immunoglobulin light chains or monoclonal immunoglobulins was demonstrated by immunofluorescence microscopy in 11 patients. The most common histopathologic findings were those of mesangiocapillary glomerulonephritis, but considerable variability was observed. Lesions resembling diabetic glomerulosclerosis and amyloidosis were seen in some patients. Immunofluorescence findings in seven patients showed concomitant, equally intense staining for kappa light chain and immunoglobulin heavy chain (IgG or IgA), indicative of monoclonal immunoglobulin deposition. Specimens in the remaining cases stained predominantly for kappa light chain alone. In six cases the histologic and ultrastructural pattern was similar to that of type I mesangiocapillary glomerulonephritis. In three cases linear deposits were present, predominantly in subendothelial and inner glomerular basement membranes and, to a lesser degree, in mesangial locations, as in type II mesangiocapillary glomerulonephritis. In one of the latter cases dense deposits were intermixed with aggregates of amorphous fibrillar material indistinguishable from amyloid. In two cases involving IgA kappa chain deposition the histologic and ultrastructural appearance was that of mesangial glomerulonephritis. Considerable heterogeneity was found in the clinical features of the patient population. Specific clinical or serologic parameters for this disease could not be identified. Only one patient had an associated lymphoplasmacytic disorder. After follow-up periods ranging from six months to 17 years, all of the patients were alive, including four who had progressed to end-stage renal disease and required dialysis. Two of the latter patients underwent successful renal transplantation; one had been alive for five years and the other for three months without evidence of recurrence of the renal disease at the last follow-up examination.     

Molecular properties of T lymphoma immunoglobulin. I. Serological and general physicochemical properties.

Immunoglobulin (Ig) released into the medium by monoclonal continuously cultured murine T lymphoma cells of the lines WEHI-22 and WEHI-7 was isolated by serological precipitation or solid-phase immunoadsorption techniques. The intact immunoglobulin had an electrophoretic mobility on sodium dodecyl-sulphate (SDS) containing polyacrylamide gels comparable to that of IgG (mass 150,000). This mobility was significantly faster than that of '7S' IgM of murine B lymphocyte surfaces. The T lymphoma immunoglobulin consisted of a pair of heavy chains linked by disulphide bonds and light chains non-covalently bound to the heavy chains. The isolated heavy chains migrated slightly faster than the mu chains of MOPC 104E IgM. Some, but not all, antisera directed against mu chains of normal mouse serum IgM bound T lymphoma immunoglobulin apparently via a cross-reaction localized to the Fd fragment. These data indicate that immunoglobulin of T lymphoma cells and, presumably normal T lymphocytes, represents an immunoglobulin isotype which is distinct from those immunoglobulins found on the B cell surface.     

Adult Fanconi syndrome with monoclonal abnormality of immunoglobulin light chain

Two adult cases of the Fanconi syndrome are described, in each of which there was abnormal urinary excretion of immunoglobulin κ-chain. The significance of this finding is discussed in relation to the recognized association between multiple myeloma and the Fanconi syndrome.