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AimThe aim of this study was to ascertain whether mannose binding lectin deficiency is implicated in coexistent rheumatoid arthritis and bronchiectasis and to determine whether undetectable mannose binding lectin confers poorer long-term survival in coexistent rheumatoid arthritis and bronchiectasis or in rheumatoid arthritis in general.Materials and methodsA retrospective audit was conducted in a rheumatoid arthritis cohort in which mannose binding lectin had been measured by enzyme linked immunosorbent assay from 2007-11. Rheumatoid arthritis patients with physician diagnosed HRCT proven bronchiectasis were recruited during this time and compared to those with uncomplicated rheumatoid arthritis. Survival from disease onset was recorded in October 2018. Kaplan-Meier survival estimates were performed to assess mortality over time in the two groups. Log rank tests were used for equality of survivor functions.ResultsThe two groups were demographically comparable. A higher frequency of undetectable mannose binding lectin was observed in coexistent rheumatoid arthritis and bronchiectasis (37.5%) compared to uncomplicated rheumatoid arthritis, (8.9%, P = 0.005). Undetectable mannose binding lectin correlated with a strong trend toward poor survival in rheumatoid arthritis overall (P = 0.057). Cox regression analysis however, showed no difference in the hazard ratio for survival between the two groups when corrected for age, gender, prednisolone use ever, rheumatoid factor status and the full range of MBL concentrations.ConclusionIn summary, undetectable mannose binding lectin is associated with coexistent rheumatoid arthritis and bronchiectasis and correlates with poor survival in rheumatoid arthritis overall. These findings further implicate immunodeficiency in the genesis of bronchiectasis in rheumatoid arthritis.

Infection is the leading cause of death in rheumatoid arthritis (RA). Corticosteroid (CS) use is a known and important risk factor for serious infections (SIs). Mannose binding lectin (MBL) is a genetically determined component of the innate immune system implicated in neonatal infections.Our aim was to determine whether MBL deficiency is a risk factor for SIs in RA and to compare it with CS use and also synthetic and biologic disease-modifying antirheumatic drug (DMARD) therapy.Data on 228 patients with RA were collected for up to 7 years (median = 5.9 years). Serum MBL concentrations were determined in all patients receiving synthetic (n = 96) or biologic (n = 132) DMARD therapy.High rates of SIs were observed in RA irrespective of treatment (17%). Similar rates of SIs were observed in synthetic and biologic DMARD users. The rates of single and multiple SIs were similar, irrespective of the use of a biologic agent. Undetectable MBL (56 ng/mL) concentrations and maintenance prednisolone at 10 mg per day or higher were associated with an increased risk for an SI, with incident risk ratio of 4.67 (P = .001) and 4.70 (P.001), respectively.Undetectable MBL and prednisolone confer a high risk for an SI. The use of biologic DMARDs did not confer substantial SI risk in this observational study. MBL deficiency is hitherto an unrecognized risk factor for an SI in RA.

Summary Aims IgG subclasses measurement is used in the investigation of patients with immunodeficiency and autoimmune diseases. In some patients a significant discrepancy between the sum of IgG subclasses (IgGsum) and total IgG may be seen. This study aimed to assess frequency and degree of such discrepancies in routine samples. Methods Data were collected retrospectively from 571 consecutive IgG subclass samples performed by an nephelometric/turbidimetric assay. Total IgG measurement was performed by nephelometry or turbidimetry. Fifty prospective samples with a difference between the IgGsum and total IgG >15% were re-run at dilution. Results IgGsum was a mean of 3.7% higher than the total IgG. Sixty-two samples (10.9%) had a difference between IgGsum and total IgG of >15%. Difference between IgGsum and total IgG correlated with the proportion but not level of IgG1. Repeat testing at dilution of samples with differences >15% did not significantly reduce the difference between results. Conclusions Differences of >15% between IgGsum and total IgG are common. Using an adjusted range based on our data would reduce the number of samples requiring additional testing. Samples falling outside this range should be reviewed.