Pravin Hissaria

B cell-intrinsic signaling through IL-21 receptor and STAT3 is required for establishing long-lived antibody responses in humans.

Engagement of cytokine receptors by specific ligands activate Janus kinase–signal transducer and activator of transcription (STAT) signaling pathways. The exact roles of STATs in human lymphocyte behavior remain incompletely defined. Interleukin (IL)-21 activates STAT1 and STAT3 and has emerged as a potent regulator of B cell differentiation. We have studied patients with inactivating mutations in STAT1 or STAT3 to dissect their contribution to B cell function in vivo and in response to IL-21 in vitro. STAT3 mutations dramatically reduced the number of functional, antigen (Ag)-specific memory B cells and abolished the ability of IL-21 to induce naive B cells to differentiate into plasma cells (PCs). This resulted from impaired activation of the molecular machinery required for PC generation. In contrast, STAT1 deficiency had no effect on memory B cell formation in vivo or IL-21–induced immunoglobulin secretion in vitro. Thus, STAT3 plays a critical role in generating effector B cells from naive precursors in humans. STAT3-activating cytokines such as IL-21 thus underpin Ag-specific humoral immune responses and provide a mechanism for the functional antibody deficit in STAT3-deficient patients.

Prevalence, correlates and clinical usefulness of antibodies to RNA polymerase III in systemic sclerosis: a cross-sectional analysis of data from an Australian cohort

IntroductionThe prevalence of antibodies to RNA polymerase III (anti-RNAP) differs among systemic sclerosis (SSc) cohorts worldwide. Previously reported associations of anti-RNAP include diffuse cutaneous disease, tendon friction rubs and renal crisis, with recent reports suggesting a close temporal association between malignancy and SSc disease onset among patients with anti-RNAP.MethodsPatients with SSc were tested for the presence of anti-RNAP at recruitment into the Australian Scleroderma Cohort Study. We used univariate and multivariable methods to identify and quantify clinical and laboratory correlates of anti-RNAP in SSc. Diagnostic testing procedures were used to determine the usefulness of these antibodies in estimating the likelihood of clinically important outcomes.ResultsThere were 451 patients with mean ± standard deviation age and disease duration at recruitment of 58.1 ± 12.4 and 11.6 ± 10.0 years, respectively; 151 (33.5%) patients were recruited within 5 years of diagnosis of SSc. Overall, 69 (15.3%) patients had anti-RNAP. Univariate associations of anti-RNAP were diffuse disease (75.4% vs. 20.9%, P < 0.0001), joint contractures (73.9% vs. 30.1%, P < 0.0001), greater highest-recorded modified Rodnan skin score (20.6 ± 12.4 vs. 10.1 ± 7.9, P < 0.0001), synovitis (31.9% vs. 19.9%, P = 0.03), myositis (2.9% vs. 0.5%, P = 0.05), systemic hypertension (59.4% vs. 39.7%, P = 0.002), renal crisis (24.6% vs. 1.8%, P < 0.0001) and malignancy diagnosed within 5 years of onset of SSc skin disease (13.3% vs. 3.9%, P = 0.01). In multiple regression analysis, after adjustment for other covariates, anti-RNAP were independently associated with renal crisis (odds ratio (OR) 3.8, 95% confidence interval (CI) 1.2 to 11.5, P = 0.02; positive predictive value (PPV) 24.6%, negative predictive value (NPV) 98.2%), diffuse disease (OR 6.4, 95% CI 2.9 to 13.8, P < 0.0001; PPV 75.4%, NPV 20.9%), joint contractures (OR 2.5, 95% CI 1.2 to 5.3, P = 0.02; PPV 73.9%, NPV 69.9%) and malignancy diagnosed within 5 years of onset of SSc skin disease (OR 4.2, 95% CI 1.3 to 13.4, P = 0.01; PPV 13.3%, NPV 96.1%).ConclusionsAnti-RNAP status is a clinically useful prognostic marker in SSc and enables clinicians to identify patients at high risk of developing renal crisis, synovitis, myositis and joint contractures. Patients with anti-RNAP also have an increased risk of malignancy within a 5-year timeframe before or after onset of SSc skin changes.

Incidence, sensitivity, and specificity of leukemia-associated phenotypes in acute myeloid leukemia using specific five-color multiparameter flow cytometry.

We assessed the usefulness of 5-color multiparameter flow cytometry to detect leukemia-associated phenotypes (LAPs) in the bone marrow of patients with newly diagnosed acute myeloid leukemia (AML) and determined its usefulness for detection of minimal residual disease (MRD). Overall, 94% of patients (51/54) with AML had LAPs at diagnosis. The frequency of leukemic bone marrow/median frequency of LAPs in normal or regenerating bone marrow samples using maximum log difference statistics revealed that CD2, CD56, CD11b, CD7, and CD19 expression on AML blasts represented the most sensitive and reliable markers for detection of MRD. Serial dilutional experiments showed that the sensitivity level of immunophenotyping was between 10-4 and 10-5 and that the approach was highly reproducible. Immunophenotypic analysis using a CD45 gating strategy, 5-color staining, and an extensive panel of monoclonal antibodies allowed the identification of LAPs in 94% of AML cases, and these immunophenotypes can be used for MRD monitoring with a sensitivity limit of 10-4 to 10-5.

CpG oligodeoxynucleotide stimulates production of anti-neutrophil cytoplasmic antibodies in ANCA associated vasculitis

BackgroundWegeners Granulomatosis and Microscopic Polyangiitis are life-threatening systemic necrotizing vasculitides of unknown aetiology. The appearance of circulating antibodies to neutrophil cytoplasmic antigens (ANCA) is strongly associated with the development of the disease. A link between infection and disease has long been suspected, and the appearance of ANCA antibodies has been reported following bacterial and viral infections. The depletion of circulating B cells with monoclonal antibody therapy can induce remission, and this observation suggests a pathogenic role for B cells in this disease. As bacterial DNA is known to induce B cell proliferation and antibody production via TLR-9 stimulation, we have explored the possibility that unmethylated CpG oligodeoxynucleotide, as found in bacterial and viral DNA, may play a role in stimulating circulating autoreactive B cells to produce ANCA in patients with vasculitis.ResultsWe have confirmed that unmethylated CpG oligonucleotide is a potent stimulator of antibody production by PBMC in vitro. The stimulation of PBMC with CpG oligonucleutides resulted in the production of similar amounts of IgG in both ANCA+ patients and normal controls. In spite of this, PR3 ANCA+ patients synthesised significantly higher amount of IgG ANCA than normal controls. In MPO ANCA+ patients, there was a tendency for patients to produce higher amount of ANCA than controls, however, the difference did not reach significance. Furthermore, we were able to detect circulating MPO-reactive B cells by ELISpot assay from the peripheral blood of 2 MPO+ ANCA vasculitis patients. Together, this indicates that circulating anti-neutrophil autoreactive B cells are present in ANCA+ vasculitis patients, and they are capable of producing antibodies in response to CpG stimulation. Of note, CpG also induced the production of the relevant autoantibodies in patients with other types of autoimmune diseases.ConclusionCirculating ANCA autoreactive B cells are present in patients with ANCA+ vasculitis. The production of ANCA from these cells in response to unmethylated CpG stimulation lead us to propose that stimulation of these cells by immunostimulatory DNA sequences such as CpG oligodeoxynucleotide during infection may provide a link between infection and ANCA associated vasculitis. This phenomenon may also apply to other antibody mediated autoimmune diseases.

Rituximab use in systemic lupus erythematosus pneumonitis and a review of current reports

Rituximab is a chimeric monoclonal antibody specific for human CD20 that causes selective transient depletion of the CD20+ B‐cell subpopulation. We report the first case of systemic lupus erythematosus (SLE) pneumonitis resistant to conventional treatments that responded well to rituximab and review current reports on the use of rituximab in SLE.

Utility of peripheral blood B cell subsets analysis in common variable immunodeficiency

Abnormalities in peripheral blood B cell subsets have been identified in common variable immunodeficiency (CVID) patients and classification systems based upon their numbers have been proposed to predict the clinical features. We analysed B lymphocyte subsets by multi‐colour flow cytometry (MFC) in a cohort of well‐characterized CVID patients to look at their clinical relevance and validate the published association of different classification criteria (Freiburg, Paris and Euroclass) with clinical manifestations. CVID patients had a reduced proportion of total and switched memory B cells (MBC, swMBC) compared to normal controls (P < 0·0006). Patients classified in Freiburg Ia had a higher prevalence of granulomatous diseases (P = 0·0034). The previously published associations with autoimmune diseases could not be confirmed. The Euroclass classification was not predictive of clinical phenotypes. The absolute numbers of all B cell subsets were reduced in CVID patients compared to controls. There was a significant linear correlation between low absolute total B cells and MBC with granulomatous disease (P < 0·05) and a trend towards lower B cells in patients with autoimmune diseases (P = 0·07). Absolute number of different B cell subsets may be more meaningful than their relative percentages in assessing the risk of granulomatous diseases and possibly autoimmunity.

Oral drug challenges in non‐steroidal anti‐inflammatory drug‐induced urticaria, angioedema and anaphylaxis

Background:  Urticaria, angioedema and anaphylaxis are common adverse reactions to non‐steroidal anti‐inflammatory drugs (NSAIDs).

Eosinophilic fasciitis as a paraneoplastic phenomenon associated with metastatic colorectal carcinoma.

A 72‐year‐old man presented with erythema and induration of his calves and forearms. He had a past history of stage 1 colorectal carcinoma, treated with resection and primary anastamosis 4 years earlier. A diagnosis of eosinophilic fasciitis was made based on the characteristic clinical appearance, peripheral blood eosinophilia and a skin biopsy. There was no improvement in the condition following treatment with prednisolone or methotrexate. One year later, abnormal liver function studies were noted, and an abdominal computed tomography scan and subsequent needle biopsy of the liver confirmed a neoplastic lesion in the liver consistent with a metastatic colorectal carcinoma. Systemic chemotherapy with oxaliplatin, 5‐fluorouracil and capecitabine was commenced, and resulted in partial remission of the colorectal carcinoma. Simultaneously, the indurations of the forearms and calves also improved, suggesting that the eosinophilic fasciitis was a paraneoplastic phenomenon.

Chronic urticaria: the autoimmune paradigm

Chronic urticaria is a disease consisting of spontaneous pruritic welts, present on all or most days for more than 6 weeks. It is commonly supposed to be allergic in origin, although allergy is not the cause in the majority of cases, and it has therefore been termed ‘chronic idiopathic urticaria’. Recent evidence indicates that at least a subset of patients in whom no extrinsic or internal cause can be identified are in fact autoimmune in origin. This is based mainly on the detection of pathogenic autoantibodies to the high‐affinity immunoglobulin E receptor FcɛR1, which are thought to activate cutaneous mast cells. In this article, we review the evidence that has given rise to this autoimmune ‘paradigm’ and its impact on diagnosis and management.

Autoimmune limbic encephalitis with anti-contactin-associated protein-like 2 antibody secondary to pembrolizumab therapy

Immune checkpoint inhibitors such as Pembrolizumab are used to restore antitumour immune response. It is important to be vigilant of immune mediated adverse events related to such therapy. We report a case of autoimmune limbic encephalitis with Contactin-Associated Protein-like 2 (CASPR2) antibody secondary to Pembrolizumab therapy for metastatic melanoma.