Plasma cell dyscrasia with marrow fibrosis. Clinicopathologic syndrome

Five new cases of plasma cell dyscrasia with coexistent myelofibrosis are described and six previously reported cases are reviewed. Four of the new patients and two from the literature had features of a previously unrecognized syndrome. This syndrome was characterized by significant paraprotein levels, marked marrow fibrosis, and plasmacytosis, without features of extramedullary hematopoiesis (agnogenic myeloid metaplasia) and leukoerythroblastosis. These patients were generally severely anemic and commonly leukopenic and thrombocytopenic. In contrast, one of the new patients and four in the literature showed classic features of the myeloproliferative disease, myelofibrosis with agnogenic myeloid metaplasia, along with features of typical multiple myeloma.     

Non-H-2 antigens on fibroblasts and an embryocarcinoma cell line react with xenoantisera against H-2 antigens.

The murine embryocarcinoma cell line F9 lacks the classical transplantation antigens. However, rabbit anti-H-2 antigen sera, recognizing "backbone structures" of H-2 K and D antigens, react with three types of molecules manufactured by F9 cells. A 49,000- and a 25,000-dalton chain are glycoproteins located on the cell surface. The third component with an apparent molecular weight of 15,000, and the 25,000-dalton chain seem to be unrelated to the 49,000-dalton glycoprotein. The 25,000- and 15,000-dalton components are not manufactured by splenocytes, thymocytes, hepatocytes, or various lymphoma, mastocytoma, and plasmacytoma cell lines. However, fibroblasts derived from both embryos and adult animals synthesize 25,000- and 15,000-dalton molecules reactive with the rabbit anti-H-2 antigen sera. The 49,000-, 25,000-, and 15,000-dalton molecules are not recognized by a syngeneic anti-F9 cell serum.     

Polyneuropathy with monoclonal gammopathy: glycolipids are frequently antigens for IgM paraproteins.

Immunoglobulins from patients with paraproteinemic polyneuropathy were screened for reactivity with nerve and brain glycolipids by ELISA and/or a thin-layer-chromatogram-overlay technique. The myelin-associated glycoprotein (MAG) has been shown to be an antigen in many neuropathy patients with IgM gammopathy, but this study focused on seven neuropathy patients in which the IgM paraproteins had been shown not to react with this glycoprotein. Five of these seven had IgM that reacted with components in the acidic glycolipid fraction of human sciatic nerve, and three of these IgMs also reacted with components in the acidic glycolipid fraction of human brain. Little or no reactivity with glycolipids was detected for two patients with neuropathy and IgG gammopathy or for two with neuropathy and IgA gammopathy. The results suggest that neuropathy-patient IgM paraproteins not reactive with MAG often react with acidic glycolipids and thus define a subset of paraproteinemic neuropathies. Since the IgM paraproteins that react with MAG also react with acidic glycolipids of nerve, glycolipid antigens appear to be quite common among the IgM paraproteinemic neuropathies.     

Ion mobility–mass spectrometry reveals the role of peripheral myelin protein dimers in peripheral neuropathy

Peripheral myelin protein (PMP22) is an integral membrane protein that traffics inefficiently even in wild-type (WT) form, with only 20% of the WT protein reaching its final plasma membrane destination in myelinating Schwann cells. Misfolding of PMP22 has been identified as a key factor in multiple peripheral neuropathies, including Charcot-Marie-Tooth disease and Dejerine–Sottas syndrome. While biophysical analyses of disease-associated PMP22 mutants show altered protein stabilities, leading to reduced surface trafficking and loss of PMP22 function, it remains unclear how destabilization of PMP22 mutations causes mistrafficking. Here, native ion mobility–mass spectrometry (IM-MS) is used to compare the gas phase stabilities and abundances for an array of mutant PM22 complexes. We find key differences in the PMP22 mutant stabilities and propensities to form homodimeric complexes. Of particular note, we observe that severely destabilized forms of PMP22 exhibit a higher propensity to dimerize than WT PMP22. Furthermore, we employ lipid raft–mimicking SCOR bicelles to study PMP22 mutants, and find that the differences in dimer abundances are amplified in this medium when compared to micelle-based data, with disease mutants exhibiting up to 4 times more dimer than WT when liberated from SCOR bicelles. We combine our findings with previous cellular data to propose that the formation of PMP22 dimers from destabilized monomers is a key element of PMP22 mistrafficking.

The misfolding of membrane proteins is implicated in the mechanisms of multiple debilitating diseases such as cystic fibrosis and retinitis pigmentosa (1–4). Specific membrane protein mutations are often associated with disease states, with variant forms exhibiting altered stability and cellular trafficking (5). Unfortunately, due to the challenges associated with preparing and handling pure, highly concentrated membrane protein samples, detailed structural information on such targets is often lacking, especially for disease mutant forms. Furthermore, as some membrane proteins associated with misfolding-based diseases have hundreds of mutations of interest (3), there is a clear need for high-throughput methods to assess disease mutation-induced changes in membrane protein stability and structure.Peripheral myelin protein 22 (PMP22) is such a membrane protein, for which misfolding and trafficking of mutant variants have been implicated in disease (6). PMP22 is a tetra-span integral membrane glycoprotein predominately expressed in Schwann cells, which are the principal glial cells of the peripheral nervous system (PNS), where they produce myelin (7–9). In addition to accounting for ∼5% of the protein found in the myelin sheath surrounding PNS nerve axons, PMP22 is thought to regulate intracellular Ca²⁺ levels (10), apoptosis (11), linkage of the actin cytoskeleton with lipid rafts (12), formation of epithelial intercellular junctions (13), myelin formation (14), lipid metabolism, and cholesterol trafficking (15). Dysregulation and misfolding of PMP22 has been identified as a key factor in multiple neurodegenerative disorders, such as Charcot-Marie-Tooth disease types 1A and E, as well as Dejerine–Sottas syndrome (6, 16–18). Like a number of other disease-linked membrane proteins (19), the trafficking of PMP22 is known to be inefficient, with only 20% of the wild-type (WT) protein reaching its final plasma membrane destination in Schwann cells (16, 20). Previously, it has been shown through a range of biophysical analyses that disease-associated PMP22 mutations lower thermodynamic protein stability as the root cause of reduced trafficking and loss of protein function; however, the mechanism by which destabilization of PMP22 causes mistrafficking is still not well understood (6). Additionally, a high-resolution structure of PMP22 has not yet been published.Native mass spectrometry (MS) has recently been demonstrated to overcome sample purity and concentration barriers to reveal critical details of membrane protein structure and function (21–23). Through the use of nano-electrospray (nESI), intact membrane proteins are ionized within detergent micelles or other membrane mimetics (24–27), which can then be removed from the membrane protein ions within the instrument. This method has been used to elucidate oligomeric state (28–30), complex organization (31, 32), and lipid interactions (33–35) of diverse membrane proteins. The addition of ion-mobility separation–mass spectrometry (IM-MS) provides data on the orientationally averaged size of analytes (36) and enables collision induced unfolding (CIU) experiments (37). In CIU, the energies experienced by gas-phase protein ions are increased in a stepwise fashion causing gas-phase protein unfolding to occur. These dynamic measurements have been shown to be sensitive to ligand binding (38, 39), glycosylation (40, 41), and disulfide bonding (40) in soluble proteins, as well as selective lipid and small molecule binding in membrane proteins (42–45). While CIU can clearly capture subtle structural changes in membrane proteins (43, 45, 46) and soluble mutant protein variants (47, 48) its ability to characterize membrane protein variants is only beginning to be explored.Here, we demonstrate the ability of native MS and CIU to detect key differences in the gas-phase stability and homodimer complex formation of PMP22 variants, together leading to insights into the mechanism of PMP22 dysregulation in disease. We quantify the propensity of PMP22 to dimerize across WT and seven disease-associated point mutations. We find that mutations associated with severe disease states form significantly more dimer than WT. Through CIU, we quantify the stability of gas-phase monomeric and dimeric PMP22 and find that variants bearing mutations associated with severe neuropathy exhibit the lowest relative monomer conformational stability. Interestingly, we also observe that dimers formed by various disease mutant forms of PMP22 are all more stable than WT PMP22 dimeric complexes. We continue by comparing our results to previously published biophysical datasets and find that our monomeric PMP22 gas-phase stability values correlate well with cellular trafficking data (6). Finally, we probe the effects of solubilization agents on PMP22 by characterizing its dimerization within sphingomyelin and cholesterol rich (SCOR) bicelles (49). We find that dimeric PMP22 complexes persist within SCOR bicelles and that the mutants resulting in the most severe disease phenotypes form higher population of dimer than WT. We conclude by describing a possible mechanism of PMP22 dysregulation in severe neurodegenerative diseases by which PMP22 monomers are destabilized, leading to dimers that traffic much less efficiently to the plasma membrane than WT PMP22.     

Plasma cell dyscrasia with arteriopathy, polyneuropathy, and endocrine syndrome. A Japanese disease in an Italian patient]

Japanese authors have described a new syndrome: plasma cell dyscrasia with polyneuropathy and endocrine disorders. So far this syndrome has been found only in Japanese patients. A new case, with diffuse arteriopathy and mediacalcosis, has been seen in a yound italian patient.     

Atypical B cell dyscrasia with Bence-Jones proteinuria and intracellular retention of gamma-chains.

A case of atypical B cell dyscrasia is described. The patient presented with a history of weakness, bone pain, and bleeding. A K-type paraprotein was found in serum and urine. The histology of bone marrow was that of a malignant lymphoma, but no enlargement of peripheral lymphoid organs was detectable. Peripheral blood lymphocytes were increased in number and included two populations of immature cells, one lymphoid and the other lymphoplasmocytoid. Immunofluorescent staining showed both populations to contain K and gamma chains in their cytoplasm. The clinicopathological heterogeneity suggests a malignant clone of B cells undergoing incomplete maturation, with arrest at different stages of the cell cycle.     

Autoimmune reactions in patients with M-component and peripheral neuropathy.

A study of 17 patients with autoimmune axonal or demyelinating peripheral neuropathy in combination with M-component is described. The M-component was associated with MGUS (monoclonal gammopathy of undetermined significance) in 12 patients, CLL in one patient, WaldenstrÖm's disease in one patient, and myeloma in three patients. Immunohistological examination with direct and indirect fluorescence showed binding of antibodies to nerve structures of the same class and light chain as seen in the M-component. In five cases of IgM M-component, the demyelinating neuropathy was caused by binding of the IgM M-protein and complement C3b to myelin-associated glycoproteins (MAG). In 12 cases with axonal neuropathy, binding of IgG to the connective tissue of the peri- and endoneurium was found in 50% of cases, IgM in five cases, and IgD in one case. None of the patients had central nervous system (CNS) symptoms. The clinical and therapeutic difficulties are discussed; only two patients with an acute course responded to immunosuppression. A marked co-expression of other autoimmune phenomena is interpreted in the light of cross-reactions between the autoantibody and similar tissue autoantigens.     

I and i antigens of human peripheral blood lymphocytes cocap with receptors for concanavalin A.

Surface immunofluorescence experiments using a human anti-i and two anti-I antisera have been performed on human peripheral blood lymphocytes. These are known to contain cold-reactive monoclonal IgM antibodies against the carbohydrate sequence: (formula: see text). A high proportion of B- and T-type lymphocytes express these I and i determinants. In the presence of anti-human immunoglobulin, the cold-reactive membrane-associated complexes of I-anti-I and i-anti-i become stabilized, and redistribution (with patching and capping) can be elicited at 37 degrees C. Dual fluorescence experiments have shown striking concordant staining of I or i (fluorescein) caps and patches with concanavalin A (rhodamine) reactive sites on normal and leukemic cells, suggesting that a proportion of I and i active structures of lymphocyte membranes are structurally associated or physiologically coupled with glycoproteins carrying oligosaccharides with branched mannosyl cores.     

Plasma cell dyscrasia with polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes: the POEMS syndrome. Report on two cases and a review of the literature

Two patients with plasma cell dyscrasias, manifested by osteosclerotic bone lesions and small amounts of M protein, and a complicating multi-system disorder are described. Their features of severe sensory-motor polyneuropathy, organomegaly, endocrine dysfunction, anasarca, elevated CSF protein, and skin hyperpigmentation are similar to a clinical syndrome reported primarily in Japanese men. Two previously unrecognized findings--hyperprolactinemia and an unusual radiographic abnormality of fluffy, spiculated bony proliferation--may facilitate recognition of the syndrome. The relationship of these various manifestations to the plasma cell dyscrasia is unknown, but a number of possibilities are discussed.     

Plasma cell neoplasia with peripheral polyneuropathy. A study of five cases and a review of the literature

Peripheral polyneuropathy (PPN) is a rare complication of plasma cell neoplasia (PCN), occurring in less than one percent of the patients. Fifty-four such patients (including our 5) were reviewed. There were 42 men (78%) and 12 women (22%) aged 28 to 72 years. Forty-nine percent of patients were younger than 51 years at the time of diagnosis. The initial complaints were different from those observed in multiple myeloma in general, and were related to polyneuropathy in 80% of the patients. PPN was usually of a mixed sensory-motor type and most often involved all four extremities. Skeletal pain was less common than in myeloma in general, occurring initially in 15% and at diagnosis in 45% of the patients. In 21 patients, reversibility of neuropathy was observed. These patients were compared to those with irreversible neuropathy and found to be relatively younger and more aggressively treated with irradiation and modern chemotherapy. Elevated sedimentation rate was uncommon. Less than half of the patients had anemia, and six patients, all with osteosclerotic lesions, had polycythemia. Azotemia was detected in 44% of the cases. No hypercalcemia was observed in 21 examined patients. M components were usually of IgG class, and when the light chains of M components were examined they were invariably of lambda type. Often the level of M component was below 2.0 g/dl. In all patients the bone marrow was infiltrated with immature, abnormal-looking plasma cells, but the infiltrate was often limited to one or a few foci. Solitary plasmacytoma was observed in 14 patients. No anemia, hypercalcemia or azotemia was recorded in this group. Eight patients had serum M components. Bone marrow aspirate was usually normal. In seven patients definite reversibility of PPN was observed after irradiation of plasmacytoma. Twelve patients presented with osteosclerotic lesions (22%), 18 with both osteosclerotic and osteolytic lesions (33%) and 13 with osteolytic lesions. Forty-two percent of the patients had less than three visible lesions in the skeleton. Eleven patients had either osteoporosis or radiologically normal skeleton. The mean survival from the first symptom was about 28 months and from the diagnosis 20 months. The five-year survival was 21% and 20%, respectively. These observations highlight the differences between PCN with PPN and multiple myeloma without PPN.     

Giant cell arteritis and peripheral neuropathy: a report of 2 cases and review of the literature

Giant cell arteritis (GCA) is a systemic vasculitis primarily affecting large and medium sized vessels. While the disease may present with blindness or other signs of extracranial vasculitis, symptoms referable to the peripheral nervous system are uncommon. We describe 2 patients with biopsy proven GCA who simultaneously developed peripheral neurologic lesions. The first developed a mononeuritis multiplex superimposed on a diffuse, primarily sensory and distal polyneuropathy; the second, a symmetric, primarily motor and distal polyneuropathy. We review the published experience of GCA with peripheral nerve involvement and discuss a possible pathophysiologic basis for its occurrence.     

Clinical and immunochemical studies of 20 patients with amyloidosis and plasma cell dyscrasia

Amyloidosis associated with plasma cell dyscrasia (AAPCD) is a relatively rare clinical entity (4% of our patients with PCD) and its early recognition and distinction from multiple myeloma (MM) may be of great therapeutic and prognostic significance. Laboratory parameters, such as concentrations of normal polyclonal Ig, Bence-Jones proteins and serum monoclonal components (MC) showed in our patients lower MC concentrations than in MM, lambda-L-chains and of gamma-H-chains predominating. Sequential skeletal X-ray studies and bone marrow morphology remain essential diagnostic procedures. Due to the lack of efficient therapeutic agents for AAPCD and the great progress achieved in recent years in the treatment of secondary amyloidosis, the immunochemical analysis of the isolated amyloid fibril as well as of the surrounding 'ground substance' should be pursued in AAPCD. Our data support previous observations, that in AAPCD the amyloid fibril subunit is an L-chain fragment predominantly derived from lambda-L-chains which originates from the same clone as the MC. The localization of an enzymatic cleavage point on the L-chain, the detection of a specific proteolytic enzyme and the identification of additional components in the amyloid substance, may further elucidate the etiopathogenesis of AAPCD.     

Chronic neutrophilic leukemia (CNL) with karyotypic abnormalities associated with plasma cell dyscrasia: a case report.

A case of chronic neutrophilic leukemia (CNL), a rare myeloproliferative syndrome associated with monoclonal gammopathy of uncertain significance (MGUS-Type IgGk), is reported. Karyotypic study, carried out on bone marrow, excluded Philadelphia-pos. chronic myeloid leukemia (CML) and showed Y loss (45 XO). Only a few cases of CNL with paraproteinemia have been reported, but no case of associated karyotypic abnormalities and paraproteinemia has so far been described.     

Natural antibodies in Microtus fortis react with antigens derived from four stages in the life-cycle of Schistosoma japonicum.

The levels of antibodies which react with the cercarial antigens (CA), schistosomulum stage antigens (SSA), adult-worm antigens (AWA) and soluble egg antigens (SEA) of Schistosoma japonicum were investigated in Microtus fortis and albino mice, using an indirect ELISA. The M. fortis studied fell into three groups: animals caught in the wild; laboratory-bred animals left unchallenged; and laboratory-bred animals that had been challenged with S. japonicum (30 cercariae/animal) 15 days previously. There were also three groups of albino mice: those without infection; those studied 15 days after challenge infection; and those investigated 42 days after infection. The antibodies detected at the highest levels in the laboratory-bred, uninfected voles and in the wild-caught animals were those reacting with SSA, followed, in descending order, by those reacting with AWA, CA and SEA. The levels of natural antibodies to SSA and AWA in these voles were significantly higher than the corresponding levels observed in the uninfected mice and even in the mice infected 15 days previously. The levels of antibodies reacting with CA, SSA, SEA and AWA in the experimentally infected M. fortis were 1.9-, 2.2-, 1.5- and 2.1-fold higher, respectively, than those in the laboratory-bred but uninfected voles. The observations indicate that even uninfected M. fortis produce antibodies which react with S. japonicum, and this presumably results in the natural resistance to infection which has been reported in these rodents.     

Immunocytochemical localization of rat peripheral nervous system myelin proteins: P2 protein is not a component of all peripheral nervous system myelin sheaths.

Specific antibodies have been developed against P1, P2, and P0 myelin proteins and were used to study the localization of these proteins in the rat peripheral nervous system. Both peripheral and central nervous system myelin sheaths contain P1 protein. P0 and P2 proteins are found exclusively in peripheral nervous system myelin sheaths. Antisera to P1 and P0 proteins stain all peripheral nervous system myelin sheaths uniformly. P2 protein is not a component of all peripheral nervous system myelin sheaths. In sheaths that do contain P2 protein, it is concentrated in the area of the Schmidt-Lanterman incisures.