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Sera of IgA nephropathy patients contain a heterogeneous population of relatively cationic alpha-heavy chains

Shuib AS, Chua CT, Hashim OH

Nephron, 1998;78(3):290-5.
PMID: 9546689

Sera of IgA nephropathy (IgAN) patients and normal subjects were analysed by two-dimensional (2-D) gel electrophoresis. Densitometric analysis of the 2-D gels of IgAN patients and normal subjects revealed that their protein maps were comparable. There was no shift of pI values in the major alpha-heavy chain spots. However, the volume of the alpha-heavy chain bands were differently distributed. Distribution was significantly lower at the anionic region in IgAN patients (mean anionic:cationic ratio of 1.184 +/- 0.311) as compared to normal healthy controls (mean anionic:cationic ratio of 2.139 +/- 0.538). Our data are in support of the previously reported findings that IgA1 of IgAN patients were lacking in sialic acid residues.

Matched MeSH terms: Immunoglobulin Heavy Chains/blood*
Heavy/light chain assay in the monitoring of multiple myeloma

Ting HY, Sthaneshwar P, Bee PC, Shanmugam H, Lim M

Pathology, 2019 Aug;51(5):507-511.
PMID: 31253381 DOI: 10.1016/j.pathol.2019.04.002

Serum protein (SPE) and immunofixation electrophoresis (IFE) have been extensively validated for the routine use of identifying, characterising and quantifying monoclonal proteins. However, accurate quantitation of IgA monoclonal proteins can be difficult when they migrate in to the β fraction, due to co-migration with transferrin and complement components. The heavy/light chain (HLC) immunoassay is an additional tool for measuring intact immunoglobulin monoclonal proteins. Therefore, we aimed to examine the clinical utility of the HLC assay for the disease monitoring of IgG and IgA multiple myeloma (MM) patients. A total of 177 samples from 30 MM patients (21 IgG and 9 IgA) were analysed retrospectively with median number of six follow up samples per patient (range 3-13). Serum free light chains (sFLC) and HLC were quantified using Freelite and Hevylite immunoassays. Details of M-protein concentration, β-globulin levels, total immunoglobulin levels and disease treatment response were obtained from the laboratory and patient information system. Passing-Bablok regression analysis was performed to compare (i) M-protein quantification with involved HLC (iHLC) and (ii) total immunoglobulin with summated HLC pairs for each immunoglobulin type (e.g., IgGκ+IgGλ). For 127 IgG MM samples, IgG iHLC levels showed a good correlation with SPE quantification (iHLC y=0.96x+4.9; r=0.917) and summated HLC showed a good correlation with total IgG concentration (summated HLC y=0.94x+5.74; r=0.91). In total, 95/127 (75%) IgG MM follow-up samples had an abnormal HLC ratio and 122/127 (96%) had a positive SPE, probably due to the lower sensitivity of HLC assay in detecting clonality in patients with IgG MM. Consistent with this, one patient assigned a very good partial response by International Myeloma Working Group criteria would be assigned a complete response based on HLC measurements. For 50 IgA MM samples, 42/50 (84%) had an abnormal HLC ratio. Conversely, 50/50 (100%) of M-proteins showed β fraction migration and were difficult to accurately quantify by SPE. Therefore, M-protein concentration and iHLC did not correlate as well in IgA MM (y=1.9x-8.4; r=0.8) compared to IgG MM. However, there was good correlation between total IgA and summated IgA HLC (IgAκ+IgAλ y=1.35x-0.33; r=0.95). Of the 8/50 (16%) IgA samples with a normal HLC ratio, 6/8 (75%) were consistent with the disease status being in complete remission. Interestingly, in one IgA MM patient, SPE and IFE were negative, but the serum FLC ratio and involved FLC were highly abnormal, consistent with the presence of light chain escape. Our data suggest HLC measurements could add value to the current disease monitoring of MM patients. In IgG MM patients, the M-protein level correlated well with HLC values. The HLC assay complements the serum FLC assay and is especially useful for monitoring of IgA MM patients who display M-proteins migrating in the β region on SPE.

Matched MeSH terms: Immunoglobulin Heavy Chains/blood*
A phage-displayed single chain variable fragment that interacts with hepatitis B core antigen: library construction, selection and diagnosis

Tan GH, Yusoff K, Seow HF, Tan WS

J Clin Virol, 2007 Jan;38(1):49-56.
PMID: 17074533

Phage display is an alternative method for constructing and selecting antibodies with desired specificity towards an antigen.

Matched MeSH terms: Immunoglobulin Heavy Chains/genetics*; Immunoglobulin Heavy Chains/immunology
Protein decomplexation and proteomics: A complementary assessment method of the physicochemical purity of antivenom

Tan CH, Liew JL, Chong HP, Tan NH

Biologicals, 2021 Jan;69:22-29.
PMID: 33431232 DOI: 10.1016/j.biologicals.2020.12.004

The quality of antivenom is governed by its safety and efficacy profiles. These quality characteristics are much influenced by the purity of antivenom content. Rigorous assessment and meticulous monitoring of antivenom purity at the preclinical setting is hence crucial. This study aimed to explore an integrative proteomic method to assess the physicochemical purity of four commercially available antivenoms in the region. The antivenoms were subjected to Superdex 200 HR 10/30 size-exclusion fast-protein liquid chromatography (SE-FPLC). The proteins in each fraction were trypsin-digested and analyzed by nano-ESI-liquid chromatography-tandem mass spectrometry (LC-MS/MS). SE-FPLC resolved the antivenom proteins into three major protein components of very high (>200 kDa), high (100-120 kDa) and medium (<60 kDa) molecular weights. The major components (80-95% of total proteins) in the antivenoms were proteins of 100-120 kDa consisting of mainly the light and partially digested heavy immunoglobulin chains, consistent with F(ab')2 as the active principle of the antivenoms. However, LC-MS/MS also detected substantial quantity of large proteins (e.g. alpha-2-macroglobulins), immunoglobulin aggregates and impurities e.g. albumins in some products. The method is practical and able to unveil the quantitative and qualitative aspects of antivenom protein compositions. It is therefore a potentially useful preclinical assessment tool of antivenom purity.

Matched MeSH terms: Immunoglobulin Heavy Chains
Identifying IGH disease clones for MRD monitoring in childhood B-cell acute lymphoblastic leukemia using RNA-Seq

Li Z, Jiang N, Lim EH, Chin WHN, Lu Y, Chiew KH, et al.

Leukemia, 2020 09;34(9):2418-2429.
PMID: 32099036 DOI: 10.1038/s41375-020-0774-4

Identifying patient-specific clonal IGH/TCR junctional sequences is critical for minimal residual disease (MRD) monitoring. Conventionally these junctional sequences are identified using laborious Sanger sequencing of excised heteroduplex bands. We found that the IGH is highly expressed in our diagnostic B-cell acute lymphoblastic leukemia (B-ALL) samples using RNA-Seq. Therefore, we used RNA-Seq to identify IGH disease clone sequences in 258 childhood B-ALL samples for MRD monitoring. The amount of background IGH rearrangements uncovered by RNA-Seq followed the Zipf's law with IGH disease clones easily identified as outliers. Four hundred and ninety-seven IGH disease clones (median 2, range 0-7 clones/patient) are identified in 90.3% of patients. High hyperdiploid patients have the most IGH disease clones (median 3) while DUX4 subtype has the least (median 1) due to the rearrangements involving the IGH locus. In all, 90.8% of IGH disease clones found by Sanger sequencing are also identified by RNA-Seq. In addition, RNA-Seq identified 43% more IGH disease clones. In 69 patients lacking sensitive IGH targets, targeted NGS IGH MRD showed high correlation (R = 0.93; P = 1.3 × 10-14), better relapse prediction than conventional RQ-PCR MRD using non-IGH targets. In conclusion, RNA-Seq can identify patient-specific clonal IGH junctional sequences for MRD monitoring, adding to its usefulness for molecular diagnosis in childhood B-ALL.

Matched MeSH terms: Immunoglobulin Heavy Chains/genetics*
Phage display of recombinant antibodies toward Burkholderia pseudomallei exotoxin

Nathan S, Li H, Mohamed R, Embi N

J. Biochem. Mol. Biol. Biophys., 2002 Feb;6(1):45-53.
PMID: 12186782

We have used the phagemid pComb3H to construct recombinant phages displaying the single chain variable fragment (ScFv) towards exotoxin of Burkholderia pseudomallei. Variable heavy and light chain fragments were amplified from the hybridoma 6E6A8F3B line, with a wide spectrum of primers specific to mouse antibody genes. Through overlapping extension polymerase chain reaction, the heavy and light chain fragments were linked to form the ScFv which was subsequently cloned into the phage display vector and transformed into ER2537 cells to yield a complexity of 10(8) clones. The transformants were screened by four rounds of biopanning against the exotoxin and resulted in selective enrichment of exotoxin-binding antibodies by 301 fold. The phage pool from the final round of selection displayed antibodies of high-affinity to the exotoxin as demonstrated by ELISA. Several clones were selected randomly from this pool and analysed by restriction enzyme digestion, fingerprinting and sequencing. Restriction analysis confirmed that all clones carried a 700-800 bp insert whose sequences, in general, corresponded to that of mouse IgG. Fingerprinting profiles delineated the antibodies into two families with different CDR sequences.

Matched MeSH terms: Immunoglobulin Heavy Chains/genetics
Relationship between immunoglobulin allotypes and susceptibility to nasopharyngeal carcinoma in Malaysia

Tarone RE, Levine PH, Yadav M, Pandey JP

Cancer Res, 1990 Jun 1;50(11):3186-8.
PMID: 1692255

The relationship between immunoglobulin allotypes and risk of developing nasopharyngeal carcinoma was examined in a comparative study of 50 Chinese cases and 140 Chinese controls and 50 Malay cases and 79 Malay controls residing in Malaysia. Although the most common Gm phenotype was elevated in both Chinese and Malay nasopharyngeal carcinoma patients compared to their controls, there were no significant differences between cases and controls in the distribution of Gm haplotypes in either population. There were no differences between cases and controls in the distribution of Km alleles in either population. Thus a previously reported association of Km(1) with increased nasopharyngeal carcinoma risk in Tunisia is not confirmed in two Mongoloid populations in Malaysia.

Matched MeSH terms: Immunoglobulin Heavy Chains/genetics*
Immunoglobulin Heavy Chain Gene Rearrangement in Non B-cell Haematological Malignancies

Noor Haslina MN, Marini R, Rosnah B, Shafini MY, Wan Haslindawani WM, Mohd Nazri H, et al.

West Indian Med J, 2013 Nov;62(8):701-4.
PMID: 25014854 DOI: 10.7727/wimj.2013.253

OBJECTIVE: Clonality detection through amplifying immunoglobulin heavy chain (IGH) gene rearrangements by polymerase chain reaction (PCR) is a useful tool in diagnosis of various B-lymphoid malignancies. Immunoglobulin heavy chain gene rearrangement can be an optimal target for clonality detection in B-lymphoid malignancies. In the present study, we evaluated the presence of IGH gene rearrangement in non B-cell haemato-oncology patients including T-cell acute lymphoblastic leukaemia (T-ALL), acute myeloblastic leukaemia (AML) and biphenotypic leukaemia.
MEHTODS: We studied 18 cases of haematological malignancies which comprised five patients with T-ALL, 12 patients with AML and one with biphenotypic leukaemia.
RESULTS: We found that the incidence of IGH gene rearrangement in T-ALL and AML were three (60%) and two (16.7%), respectively. The patient with biphenotypic leukaemia was negative for IGH gene rearrangement.
CONCLUSION: Immunoglobulin gene rearrangement, which occurs in almost all haematological malignancies of B-cell lineage, also presents in a very small proportion of T-cell or myeloid malignancies.

Matched MeSH terms: Immunoglobulin Heavy Chains