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At least 19 recordsLinked to original sources
PubMed1979

Identification of the paraproteins and clinical significance of more than one paraprotein and clinical significance of more than one paraprotein in serum of 56 patients.

Sera from 56 patients with more than one paraprotein were investigated for immunoglobin class and light chain type of each paraprotein. The patients were divided into two groups according to the diagnosis, that is myeloma and macroglobulinaemia or others. The frequency of combinations of paraproteins was considered in the whole series and in the two groups. The laboratory and clinical findings were analysed to investigate the diagnostic and prognostic significance of more than one paraprotein in a serum. It is concluded that a lower percentage of patients with more than one paraprotein can definitely be shown to have myeloma than might be expected from studies on monoclonal paraproteinaemia, that patients having IgA paraproteins in the serum had the poorest prognosis, and that paraproteins with lambda light chains were more likely to be associated with myeloma or macroglobulinaemia. A discriminant analysis of ESR and total paraprotein levels in the two groups of patients showed that combinations of the two parameters were not more effective at distinguishing the groups than the ESR alone.

Blood Sedimentation↗
PubMed1990

Paraproteins and primary lymphoma in SJL mice. I. Individuality of idiotypes on paraproteins.

The isotype distribution and idiotypic determinants of paraproteins (PP) found in sera from aging SJL mice were studied. One or more PP were found in 79% of 9-11 month old mice; the isotypes were gamma 1 greater than or equal to alpha greater than or equal to gamma 2a much greater than gamma 3 much greater than gamma 2b. There was a significant tendency for the PP to occur in pairs or triplets, multiple PP being found in 35% of the mice without an evident association between any two isotypes. Rabbit anti-Id was prepared against four isolated PP, two gamma 1 and two gamma 2a. Inhibition of anti-Id-Id interaction was specific for the immunizing PP only and was absent with all other PP studied (8 gamma 1 and 10 gamma 2 PP) and with normal SJL Ig. It is concluded that SJL PP fail to exhibit cross-reactive idiotypes and show a wider range of isotype distribution than was previously suspected, although PP of mu, delta, and epsilon isotypes are absent.

Animals↗
PubMed1990

Paraproteins and primary lymphoma in SJL mice. II. Primary lymphomas do not produce paraprotein.

The incidences of Ig paraprotein (PP) and reticulum cell sarcomas (lymphomas) were studied in a group of 75 SJL mice, 9-11 months of age. PP and lymphoma were observed in 52% of the mice. PP alone was observed in an additional 27% and lymphoma alone in an additional 11% of mice. In attempts to establish a causal relationship between lymphomas and PP, three approaches were used: (a) Serum PP levels were followed during lymphoma growth in primary lymphoma bearing mice and found to decrease rather than to increase. (b) Recipients of primary transplants were examined for appearance of PP-related idiotypes (Id) in their sera and for lymphoma growth. The Id appeared early (Day 10-11) and then disappeared, while lymphoma growth usually was detectable by greater than or equal to 1 month. (c) One of the primary lymphomas was propagated as a tissue culture line and found not to produce any PP or intact Ig. It is concluded that the PP of SJL mice are not produced by their lymphomas. Other possible relationships are discussed, including the role of the PP as a symptom of a prelymphomatous stage that develops in a very high percentage of SJL mice.

Animals↗
PubMed1993

The paraproteins in systemic capillary leak syndrome.

Systemic capillary leak syndrome (SCLS) is a rare disease characterized by episodes of collapse due to rapid transfer of considerable volumes of plasma from the intravascular to the extravascular compartment. The pathogenesis of this disease is unknown. The diagnosis is made largely on clinical grounds, and investigations are unhelpful. The only consistent abnormality is that an IgG paraprotein is found in most patients, raising the possibility that the paraprotein may be involved in the pathogenesis of the disease. Reduction of the paraprotein level in our patient was associated with remission. Blood samples from three SCLS patients and one probable SCLS have been studied. All patients had monoclonal IgG paraproteins. The purified paraproteins were all of IgG1 subclass and had kappa light chains. However, they differed in size and charge. Antibodies against each of the paraproteins were raised in rabbits. Affinity-purified anti-idiotypic antibodies were tested for cross-reactivity against the other paraproteins using immunoblotting and Ouchterlony assay. These assays showed that the anti-idiotypic antibodies reacted only with the immunizing paraprotein and not with any of the other paraproteins, i.e. that the paraproteins do not share a common idiotype. Paraproteins did not bind to cultured endothelial cells, either unactivated or following activation with interferon-gamma (IFN-gamma), IL-2 or IL-6. In addition, we were unable to demonstrate any cytotoxicity towards cultured human endothelial cells by paraprotein alone, or in the presence of neutrophils (pronounced neutrophilia being a feature of attacks). The relationship between the paraproteins and the disease remains unclear. It is likely that additional, as yet unidentified, factors are required for the paraprotein to lead to capillary leak.

Blood Protein Electrophoresis↗
PubMed1996

[Isotypic characterization of IgA paraproteins: association with other clinical and analytic data].

A study was conducted to investigate the relationships between the characteristics of IgA paraprotein and the clinical findings in a group of 196 patients. In 19 cases IgA paraprotein was associated with another monoclonal immunoglobulin (IgG or IgM); the other 177 patients had a single IgA paraprotein; 145 of them corresponded to multiple myeloma (MM) and the other 32 to other diagnostics. Class and type of paraproteins were identified by immunoelectrophoresis and subclass by an enzyme-immunoassay specifically developed for this study. The degree of polymerization of the protein was determined by gel filtration; quantitation of monoclonal IgA and polyclonal IgG and IgM was obtained by kinetic nephelometry. Out of 196 paraproteins, 96.4% were classified in IgA1 subclass and only 3.6% in IgG2. In 14 cases, all of them diagnosed with MM, monoclonal IgA in serum was associated with Bence-Jones protein; in more than 78% of them light chains corresponded to type lambda, whereas type kappa predominated (over 60%) in cases without Bence-Jones protein in serum. Significantly higher serum levels of monoclonal IgA were associated with the diagnosis of myeloma, with type kappa paraproteins, and with the presence of Bence-Jones protein in serum. The cases with two paraproteins (IgA and IgG or IgM) had significantly lower serum levels of IgA, with comparable levels of total paraprotein (the addition of both monoclonal immunoglobulins). Serum levels of polyclonal IgG and IgM, which appeared decreased in cases of MM, were normal in cases with other conditions. In all these cases, monoclonal IgA showed a monomeric character, whereas relevant amounts of polymerized IgA paraprotein was found in almost a third part of myeloma cases, particularly in those with higher serum levels of paraprotein, or when paraprotein belonged to type kappa. The 5 IgA2 paraproteins analyzed had a polymeric character. In conclusion, a detailed, both qualitative and quantitative, analysis of IgA paraproteins can lead to a better knowledge of conditions associated with their presence and at the same time provides useful data for a clinical evaluation of patients.

Humans↗
PubMed1989

Precision and reliability of paraprotein determinations by high-resolution agarose gel electrophoresis.

Agarose gel electrophoresis has recently replaced cellulose acetate electrophoresis as the preferred technique for monitoring paraprotein levels in patients with plasma cell dyscrasias. The authors studied the accuracy and precision of this method for paraprotein determination. Twenty-seven serum samples with paraprotein concentrations ranging from 5 to 73 g/L were aliquotted and assayed on 20 separate occasions, and the mean and standard deviation for the paraprotein concentration in each serum was established. Linear regression analysis showed that the standard deviation of paraprotein concentration (SD) increased as a function of paraprotein concentration (PC). For IgG paraproteins, the regression equation was SD = 0.041 (PC) + 1.06; R = 0.942; standard error = 0.32. For non-IgG paraproteins the equation was SD = 0.101 (PC) - 0.04; R = 0.851; standard error = 0.5. The accuracy of paraprotein determinations by the agarose gel electrophoretic technique was assessed by comparison with values obtained with the use of a previously validated enzyme-linked immunosorbent assay (ELISA) method for quantitation of IgG subclasses. Results obtained by the two methods were similar and highly correlated: (concentration by electrophoresis) = 0.921 (concentration by ELISA) + 0.46; R = 0.988; standard error = 0.34. The laser densitometric scanning procedure showed a loss of linearity above 60 g/L, indicating the need to dilute sera with very high paraprotein concentrations in order to obtain accurate results. A table is presented that should help pathologists who interpret such scans to determine whether small changes in paraprotein measurements occurring over time represent true changes in paraprotein concentration or merely reflect the analytic variability inherent in the technique.

Densitometry↗
PubMed2002

Paraproteins: a regional South Australian experience.

We have performed a systematic review of all new serum and urinary paraproteins detected over a six year period in an immunodiagnostic laboratory serving a population of 400,000 people. Clinical diagnoses and associated laboratory features were ascertained from a computerized laboratory database or from clinical notes. Over the period of study, serum or urine paraproteins were detected in 613 new patients. These consisted of 568 patients with serum paraproteins and 45 patients with urinary monoclonal free light chain (in the absence of a serum paraprotein). These paraproteins occurred more commonly in males and the frequency increased with age. Approximately 30% of the serum paraproteins and 60% of urinary monoclonal free light chain were associated with B cell lymphoproliferative disorders (multiple myeloma, plasmacytoma, Waldenstrom's macroglobulinemia, non-Hodgkins lymphoma, chronic lymphocytic leukemia, etc) with the remainder being labeled as monoclonal gammopathies of uncertain significance (MGUS). At clinical presentation, patients with lymphoproliferative disorders tended to have higher levels of paraprotein, B2 microglobulin, the presence of free urinary light chain and demonstrated molecular size heterogeneity of the paraprotein but there was considerable overlap. A good correlation was noted between paraprotein concentration and viscosity in most patients. In conclusion paraproteins were most frequently encountered in the context of a gammopathy of uncertain significance. Features which suggested lymphoproliferative disorders included higher levels of serum paraprotein (> 15 g/l), elevated levels of B2-microglobulin and the presence of urinary free high chain. However, as much overlap was seen with patients with MGUS, regular monitoring of paraprotein level is considered mandatory in the management of these patients.

Adult↗
PubMed1988

High titer anti-HIV antibody reactivity associated with a paraprotein spike in a homosexual male with AIDS related complex.

We observed a human immunodeficiency virus (HIV)-infected homosexual male with AIDS related complex (ARC) who had a serum globulin level of 80 g/L. Serum protein electrophoresis revealed a gamma globulin fraction of 40 g/L, of which 50% (20 g/L) was contained within a paraprotein spike, comprised predominantly of IgG kappa. This patient also had high titer anti-HIV antibodies in his serum, which were Western blot reactive at a final dilution of 1:500,000, and recognized gp120env, p66pol, p55gag, p53pol, p41gag, and p24gag. Because paraproteins in the past have been shown to be directed against specific antigens, we purified this patient's paraprotein using a modified high performance liquid chromatography (HPLC)-hydroxylapatite procedure and tested the purified paraprotein for anti-HIV antibody activity. The purified paraprotein retained anti-HIV antibody activity to a final dilution of 1:100,000, and recognized p66pol, p55gag, p53pol, p41gag, and p24gag. The recognition of both "gag" and "pol" gene products suggested that the purified paraprotein might not be monoclonal in origin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that the purified paraprotein contained at least two immunoglobulin light chain species (Mol wt 30 to 33 Kd). Affinity chromatography of the purified paraprotein using a p24-Sepharose 4B matrix separated the "gag" and "pol" antibody activities. Immunoglobulin gene rearrangement analysis of a bone marrow aspirate (which contained 15% plasma cells) failed to reveal a clonal population of immunoglobulin producing cells. We conclude that this patient's paraprotein accounted for most of the anti-HIV activity present in whole serum, and that this paraprotein was not monoclonal in origin.

AIDS-Related Complex↗
PubMed1995

Kinetics of paraprotein clearance after autografting for multiple myeloma.

The kinetics of paraprotein clearance after autografting for multiple myeloma have not been described. We studied 33 myeloma patients in plateau phase with detectable paraprotein (3-34 milligrams, median 10 milligrams) at the time of ABMT who received melphalan (200 mg/m2) and methylprednisolone (1.5 g x 5) for conditioning. Fifteen patients received interferon-alpha post-transplant as part of a randomized study. Twenty-four of 33 (72.7%) patients eventually cleared the paraprotein at a median of 47 days (range 5-783) post-transplant. The probability of clearance was lower (46.7 vs 94.4%, P = 0.004) and the time taken to clear paraprotein longer (142 vs 29 days, P = 0.003) in patients with a higher level (> 10 milligrams) at the time of the transplant. However, clearance occurred within 6 months in 23 of 24 (95.8%) patients who ultimately cleared the paraprotein. Interferon-alpha did not influence the clearance of paraprotein. We conclude that after autografting for myeloma, the time taken to clear paraprotein is longer and the probability of clearance lower with higher levels at the time of ABMT, and most patients who eventually clear the paraprotein do so within 6 months. Because the probability of clearing paraprotein (and thus attaining remission) in patients with detectable paraprotein 6 months post-transplant is low, a decision about further treatment may be made at this point.

Adult↗
PubMed1975

[Light chain typing of paraproteins and Bence-Jones proteins by immunoelectrophoresis].

Light chain types of paraproteins G (76), A (28) and D (5), monoclonal macroglobulins (14) and Bence-Jones proteins (11) were determined by immunoelectrophoretic analysis using monospecific antisera to surface (accessible) and nonaccessible determinants of light chains. The types of the G and A paraproteins were determined in the whole sera; D paraproteins and monoclonal macroglobulins were purified before typing. No precipitation occurred with antisera to light chains in 6 out of 28 A paraproteins. In these cases the inhibition of the IgG precipitation with either the anti-kappa or anti-lambda sera allowed to determine the paraprotein type. The kappa:lambda ratio was established for paraproteins of various classes: 1.7 for paraproteins G, 1.0 for paraproteins A, 2.5 for monoclonal macroglobulins and 0.83 for Bence-Jones proteins. All the D paraproteins investigated were of the lambds-type.

Bence Jones Protein↗
PubMed1999

Monomeric complement-activating IgG paraproteins.

Three patients presented a unique syndrome of recurrent panniculitis with an IgGkappa paraprotein and depletion of the early components of the classical pathway of complement. The IgGkappa paraproteins were monomers with a normal structure, and with no evidence for aggregation, as assessed by electron microscopy and ultracentrifugation. Both heavy and light chains were of normal molecular size (SDS-PAGE), and the paraproteins were not heavily glycosylated. However, the paraproteins from all three patients had unusual features that included abnormal behavior on gel filtration chromatography and a heavy chain of high pI. When analyzed by fast protein liquid chromatography (Superdex 200), elution of the paraproteins was retarded, particularly when the ionic strength was increased. This retardation was partially reversed in 20% alcohol, and fully reversed in 6 M guanidine-HCl. Neither anti-C1 inhibitor nor anti-C1q autoantibodies were found in any of the patients' sera. However, the paraproteins bound to the globular heads of C1q at normal ionic strength. They activated C4 in normal human serum, but not in C1q-deficient serum. Activation led to the formation of C1s-C1 inhibitor complexes. Taken together, the data suggest that the unusual paraproteins have the capacity to bind C1q, which then leads to activation of C1. The ability of these paraproteins to activate C1, in spite of their being soluble monomers, is likely to be related to their unique physicochemical features.

Chromatography, Gel↗
PubMedDate not supplied

Rheumatic autoantibodies in the sera of patients with paraproteins.

OBJECTIVE: A high incidence of autoantibody activity has been previously described in the sera of patients with paraproteins. In this study we determined the incidence of autoantibodies of particular interest to rheumatologists (including antinuclear antibodies (ANA), anti-DNA, rheumatoid factor (RF), anticardiolipin antibodies (aCL) and the Sjögren's-related antibodies anti-SS.A/Ro and anti-SS.B/La) in the sera of patients with paraproteins, and the frequency with which the autoantibody activity isotype and the paraprotein isotype were identical. METHODS: ANA was determined by indirect immunofluorescence on HEp2 cells, anti-DNA by the Farr and Crithidia assays, aCL by ELISA, RF by nephelometry, antibodies to the extractable nuclear antigens (anti-ENA) by counter-immunoelectrophoresis (CIE), and anti-SS.B by immunoblot using a recombinant human SS.B antigen source. Incidences of these antibodies was compared in 3 groups of sera: 98 myeloma, 27 monoclonal gammopathy of uncertain significance (MGUS), and 24 age matched controls, using confidence interval analysis. RESULTS: There was no significant difference between the incidence of ANAs in paraprotein sera (8.8%) and control sera (16%). Neither was there a significant incidence of RF or aCL in the paraprotein sera. No anti-DNA antibodies were found and no anti-SS.B antibodies were found either with CIE or immunoblotting. Of the 11 ANAs detected in the paraprotein sera, isotype specific immunofluorescence suggested that 6 were monoclonal autoantibodies. CONCLUSIONS: These results indicate that the incidence of rheumatic autoantibodies is not raised in paraprotein sera compared to control sera. In particular, we could not confirm previous reports of a high incidence of anti-SS.B antibodies. However, of the ANAs detected half were monoclonal, unlike the polyclonality of the ANAs in the control group. That 4.8% of the paraproteins were monoclonal ANAs suggests that the process leading to paraproteinemia may activate usually silent autoreactive B cells as well as the normal B cell repertoire.

Arthritis, Rheumatoid↗
PubMed1975

[Thrombocytopenia in Waldenstrom's disease with specific antithrombocytic properties of the IgM paraprotein].

The serum of a patient suffering from thrombocytopenia associated with Waldenström's macroglobulinemia was found to contain an IgM paraprotein with unusual characteristics. Following isolation of this IgM paraprotein, dilutions up to 0.01 mg/ml caused immunofluorescence of thrombocytes from man, sheep, rabbit, and horse. In control studies with isolated IgM paraprotein from another non-thrombocytopenic patient with Waldenström's disease, positive immunofluorescence could be elicited only when a 1000-fold greater concentration of the paraprotein was used. The IgM paraprotein from our thrombocytopenic patient and that from the control patient showed comparable differences in immunofluorescence of thrombocytes and megacaryocytes when bone marrow smears were used for incubation. Further studies following papain cleavage of the IgM paraprotein with antithrombocytic activity showed that the combining activity was located in the Fab fragment. This observation characterizes the IgM paraprotein from our patient as an antibody directed to a substance in human and animal thrombocytes. Paraproteins with antibody-like activity for thrombocytes have not been identified previously; the present observation suggests that this mechanism should be considered a possible cause of thrombocytopenia associated with macroglobulinemia.

Blood Platelets↗
PubMed1989

The clinical significance of human immunodeficiency virus type 1-associated paraproteins.

We observed and characterized paraproteins present in the serum of seven human immunodeficiency virus type 1 (HIV-1)-infected individuals. Immunoglobulin (Ig) subclass typing performed on these paraproteins identified five as IgG1 kappa, one as an IgG3 lambda, and one as an IgA lambda. The IgG1 kappa paraproteins, purified by high-pressure liquid chromatography, contained the majority of anti-HIV-1 antibody reactivity present in the five serum specimens (ranging from 1:5,000 to 1:500,000) as demonstrated by immunoblot. All five IgG1 paraproteins had at least two light chain species as demonstrated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the antibodies were reactive with multiple HIV-1 viral antigens. In contrast, the electrophoretically purified IgG3 lambda and IgA lambda paraproteins did not react with HIV-1 antigens and only one light chain species was detected by SDS-PAGE. The subsequent clinical evaluation of these patients following the initial observation of paraproteinemias failed to correlate the presence of paraproteins with the development of lymphoma over a 2 to 3 year period. These data support the hypothesis that IgG1 paraproteins present in the sera of HIV-1 infected individuals reflect a normal albeit exuberant polyclonal immune response to HIV-1 viral antigens. In contrast, the clinical significance of an IgG3 lambda or an IgA lambda paraprotein is unclear at present.

Antibody Specificity↗
PubMed1995

Human immunoglobulin M paraproteins cross-reactive with Neisseria meningitidis group B polysaccharide and fetal brain.

Three hundred fifty-nine serum samples from patients with immunoglobulin M (IgM) or IgG monoclonal gammopathies were tested for binding to the capsular polysaccharide (PS) of Neisseria meningitidis group B (MenB PS, poly-alpha[2-->8]-N-acetylneuraminic acid). Of 159 IgM paraproteins, 7 (4.4%) were positive, compared with 0 of 200 IgG paraproteins (P < 0.05). Since MenB PS reactivity was limited to the IgM paraproteins, the 159 IgM paraproteins were tested by enzyme-linked immunosorbent assay (ELISA) for reactivity with seven other bacterial PSs. None reacted with meningococcal A or C, Haemophilus influenzae type b, or Streptococcus pneumoniae type 3, 6, 14, or 23 PS. The specificity of the MenB PS-reactive antibodies was confirmed by demonstration of binding to N. meningitidis group B cells but not to a capsular PS-deficient mutant and by specific inhibition of binding to solid-phase MenB PS by soluble MenB PS in an ELISA. Five of five antibodies tested protected infant rats from bacteremia caused by Escherichia coli K1, an organism with a PS capsule that also is composed of poly-alpha[2-->8]-N-acetylneuraminic acid. Each of the seven MenB PS-reactive paraproteins had autoantibody activity as defined by binding to homogenates of calf brain in a radioimmunoassay. For six of the seven antibodies, binding to calf brain was inhibited by the addition of soluble MenB PS. Thus, approximately 4% of human IgM paraproteins have autoantibody activity to poly-alpha[2-->8]-N-acetylneuraminic acid, an antigen expressed in fetal brain and cross-reactive with the MenB capsular PS. The reason for this skewing of the IgM paraprotein repertoire toward reactivity with poly-alpha[2-->8]-N-acetylneuraminic acid antigenic determinants is unknown.

Animals↗
PubMed1989

Detection and typing of paraproteins: comparison of different methods in a routine diagnostic laboratory.

In this paper we review four methods: Protein electrophoresis (PE), immunoelectrophoresis (IEP), immunofixation electrophoresis (IFE) and a nephelometric kappa:lambda ratio method for the ability, first, to detect, and second, to isotype paraproteins in urine and serum. IFE was the most sensitive assay both in the detection of paraproteins and the most accurate in their typing. The nephelometric kappa:lambda ratio was associated with false-positive and false-negative results and cannot be considered suitable for routine diagnostic use. Although IFE was the most sensitive assay it was not without problems. Dilution of the serum to produce a concentration suitable for IFE is critical, and the assay is demanding in operator skill and time. The extra paraproteins identified by IFE are generally of low concentration and with the exception of certain well-defined clinical situations are probably not of great importance in patient management. In the case of diseases where the demonstration of a small amount of paraprotein is important, such as amyloidosis, then IFE should be performed in case other techniques fail to demonstrate a paraprotein. Otherwise, IFE is best reserved for paraproteins detected by PE which cannot be typed by IEP. A schema for the management of paraprotein identification for use in a routine diagnostic laboratory is presented.

Blood Protein Electrophoresis↗
PubMed1988

Incidence of three cross-reactive idiotypes on human rheumatoid factor paraproteins.

The basis for rheumatoid factor (RF) production in autoimmune or lymphoproliferative diseases cannot be understood without defining the molecular factors that dictate RF structure and specificity. Recently three different mAb (6B6.6, 17.109, and G6) have been developed that define cross-reactive idiotypes (CRI) on intact L or H chains of human monoclonal RF cryoglobulins. However, the true incidence of these CRI among RF and their relationship to each other have not been delineated. In the present experiments, a panel of 163 randomly selected IgM paraproteins was evaluated for the expression of the two kappa L chain CRI, 6B6.6 and 17.109, and the H chain CRI, G6. Among the paraproteins with kappa L chains, 14% expressed the 17.109 CRI, and 9% expressed the 6B6.6 CRI. Both ELISA and Western immunoblotting experiments showed that the two L chain CRI were mutually exclusive. Anti-IgG activity was documented in 22 of the IgM-kappa paraproteins, among which mAb 6B6.6 reacted with 7 (32%) and mAb 17.109 with 6 (27%). Both CRI were expressed exclusively by L chains within the kappaIII variable gene subgroup. Although 17.109 CRI+ paraproteins had kappaIIIb L chains, none of the 6B6.6 CRI+ paraproteins possessed L chains with this kappa sub-subgroup specific Ag. The G6 CRI was found predominantly among RF paraproteins and was frequently yet not exclusively associated with the 17.109 CRI+ L chains. Additional experiments were performed on a panel of normal adult human sera and documented the presence of 6B6.6 and 17.109 CRI on a small percentage (0.1 to 2.0%) of IgM from most individuals. These data indicate that 1) the mAb 6B6.6 and 17.109 identify two major and distinct CRI among IgM-RF paraproteins, 2) both CRI are associated exclusively with kappaIII L chains, 3) kappaIIIb and kappaIII non-b L chains are equally prevalent among IgM-RF, 4) the G6 H chain CRI is frequently associated with 17.109 CRI+ L chains, but not with 6B6.6 CRI+ L chains, and 5) although the ability to make 6B6.6 and 17.109 CRI+ kappa L chains is common in humans, these CRI are present in low concentrations in normal IgM.

Adolescent↗