Factors associated with serum IgM concentrations: a general adult population study.

BACKGROUND AND AIM: To investigate the influence of common factors on serum immunoglobulin M (IgM) concentrations in adults, and clinical associations with high and low values. METHODS: We measured serum IgM levels using immunonephelometry in a random sample of 1510 individuals (aged 18-91 years, 44.7% male). We obtained data defining metabolic syndrome from all participants, defined atopy by skin prick tests to aeroallergens, and assessed lifestyle factors by questionnaire. RESULTS: Women showed higher IgM concentrations than men; 95 (6.3%, mostly male) individuals showed low (<0.40 g/L) IgM values, and 64 (4.2%, mostly female) showed high (>2.30 g/L) IgM values. Individuals with abnormal IgM concentrations had no history of opportunistic infections nor a different atopy prevalence. Serum IgM concentrations decreased with age, and obesity was negatively associated with IgM concentrations. Alcohol consumption, smoking, physical activity, and metabolic syndrome had no significant influence in the multivariate analyses. CONCLUSIONS: Many adults in the general population show abnormally high or low IgM concentrations with no evidence of immunodeficiency-associated diseases. Sex and age should be considered when defining reference IgM concentrations.

Factors Influencing Total Serum IgE in Adults: The Role of Obesity and Related Metabolic Disorders.

BACKGROUND AND AIM: Few reports have investigated the association between metabolic abnormalities (obesity and related metabolic syndrome) and total serum IgE concentrations. METHODS: This cross-sectional study included a random sample of 1,516 adult individuals (44.7% men, aged 18-91 years, median 52 years) from a single municipality in Spain. Serum IgE was measured in the ADVIA Centaur system. Atopy was defined by the presence of positive skin prick tests to a panel of common aeroallergens in the area. Body mass index and data related to the definition of metabolic syndrome were obtained from all participants. Alcohol consumption, smoking, and regular physical exercise were assessed by a questionnaire. RESULTS: Atopy (present in 21.9% of 1,514 evaluable individuals) was the strongest factor determining serum IgE concentrations. Male sex and heavy alcohol drinking were independently associated with higher IgE concentrations, particularly in the non-atopic individuals. Body mass index was positively associated with IgE concentrations, independent of potential confounders, although the effect was only evident among non-atopic individuals. In that group, median IgE concentrations in normal-weight and obese individuals were 15 and 24 kU/L, respectively (p < 0.001); likewise, obesity was associated with high (>100 kU/L) IgE concentrations after adjusting for potential confounders (odds ratio: 1.79, 95% confidence interval: 1.26-2.56, p = 0.001). The presence of metabolic syndrome and its components, particularly abdominal obesity and hyperglycaemia, was also positively and independently associated with higher IgE concentrations in non-atopic individuals. CONCLUSIONS: Obesity and metabolic syndrome components are associated with high total serum IgE concentrations, particularly in non-atopic individuals.

Treatment and outcomes in patients with IgG4-related disease using the IgG4 responder index.

BACKGROUND: IgG4-related disease (IgG4-RD) is an autoimmune disease triggering an inflammatory cascade that leads to fibrosis. Outcome measures are limited and treatment options remain underexplored. OBJECTIVES: To assess the variation of the IgG4 responder index (IgG4-RI) in a cohort of IgG4-RD patients and to explore their treatments and outcomes. METHODS: We studied the clinical phenotype, severity of the disease and response to treatment in an ambispective multicenter cohort study including 14 different hospitals in Spain. All patients met the 2012 international consensus on pathology criteria for diagnosis. RESULTS: Sixty-eight patients were included, with a mean age of 53.4 years and predominance of male sex. The most commonly involved tissues were: retroperitoneum (33%), orbital pseudotumor (28%) and maxillary and paranasal sinuses (24%). IgG4-RI values were higher in patients with multiorgan disease and before treatment. After being treated, IgG4-RI values were lower, in accordance with the high rates of treatment response. Most patients received: glucocorticoids (GC), surgery, azathioprine (AZA), mofetil mycophenolate or rituximab. GC alone, GC plus surgery and GC plus AZA were given in the most of the IgG4-RD disease activity episodes. All treatments had high response rates but relapses and flares were common. CONCLUSIONS: IgG4-RI is a promising outcome measure in IgG4-RD, but still in development. Treatment algorithms are ill defined. GC and rituximab are the drugs with more evidence available. Disease modifying anti-rheumatic drugs may have a role in IgG4-RD and warrant more prospective studies.

Serum Concentrations of IgG4 in the Spanish Adult Population: Relationship with Age, Gender, and Atopy.

BACKGROUND AND AIM: Serum IgG4 concentrations are commonly measured in clinical practice. The aim of this study was to investigate serum IgG4 concentrations in adults and their potential relationship with demographic, lifestyle, metabolic, and allergy-related factors. METHODS: Serum IgG4 concentrations were measured with a commercial assay in 413 individuals (median age 55 years, 45% males) who were randomly selected from a general adult population. RESULTS: Median IgG4 concentration was 26.8 mg/dL. Five out of the 413 individuals (1.2%) exhibited IgG4 concentrations >135 mg/dL, and 17 out of 411 (4.1%) exhibited an IgG4/total IgG ratio >8%. Serum IgG4 concentrations were significantly higher in males than in females and decreased with age. After adjusting for age and sex, serum IgG4 concentrations were not significantly influenced by alcohol consumption, smoking or common metabolic abnormalities (obesity and the related metabolic syndrome). Serum IgG4 concentrations were not significantly correlated with serum concentrations of proinflammatory cytokines and inflammation markers. Serum IgG4 concentrations were significantly correlated with IgE concentrations. Serum IgG4 concentrations tended to be higher in atopics (individuals with IgE-mediated sensitization to aeroallergens) than in non-atopics, particularly among atopics without respiratory symptoms. Serum IgG4 concentrations were not significantly correlated with total eosinophil blood count. Cases of IgG4-related disease were neither present at baseline nor detected after a median of 11 years of follow-up. CONCLUSIONS: Studies aimed at defining reference IgG4 values should consider partitioning by age and sex. Further studies are needed to confirm the potential influence of atopy status on serum IgG4 concentrations.