Recently, there has been an interest in the use of tacrolimus for the treatment of rheumatoid arthritis (RA). The role of rheumatoid factor (RF) as a cause of immunoassay interferences is well known. This study is the first to investigate the susceptibility of a tacrolimus immunoassay to interference by RF. Tacrolimus apparent concentrations were determined using the antibody conjugated magnetic immunoassay (ACMIA) run on the Dimension RxL Immunoassay System in 100 randomly selected samples previously submitted for routine diagnostic or monitoring of RA in patients not receiving tacrolimus. Fifty of them had an RF concentration exceeding 100 IU/L and 50 had an RF concentration below 20 IU/L. Samples with tacrolimus apparent whole-blood concentrations above 2.3 ng/mL (limit of quantification of the ACMIA assay alleged by the vendor) were considered as potential false positives. No positive tacrolimus result was found among the 50 samples with serum RF < 20 IU/mL. Among the 50 selected samples from patients with RF > 100 IU/mL (RF range 110-2650 IU/mL), 2 were positive for tacrolimus with ACMIA. In both cases, the pretreatment of these samples with an immunoglobulin blocking agent reduced the apparent tacrolimus concentrations to below the limit of detection. This was confirmed using the alternative and reference tacrolimus assays, both of which reported results below their respective limits of detection. The measured human anti-mouse antibodies levels were found to be elevated. These results show that certain patients with positive RF can have false-positive tacrolimus results using the tacrolimus ACMIA-Flex immunoassay on a Dimension RXL analyzer, which was not the case with 2 other techniques. The interference with the tacrolimus ACMIA results was suppressed after preincubation with an immunoglobulin blocking reagent.

Background: Obstructive sleep apnea (OSA) is prevalent in pregnancy and it is associated with adverse pregnancy-related outcomes such as gestational diabetes, pre-eclampsia, and low birth weight. Maternal systemic inflammation is proposed to be one of the main intermediate mechanisms. However, the effects of OSA on systemic inflammation are unknown in normal pregnancy.Methods: Women in the 3rd trimester underwent hospital polysomnography to evaluate whether OSA increases systemic inflammation in normal pregnancy and its potential association with adverse fetal outcomes. OSA was defined as an apnea–hypopnea index (AHI) of ≥ 5 h−1. Plasma cytokines levels (TNF-α, IL-1β, IL-6, IL-8, and IL-10) were determined by multiple immunoassays.Results: We included 11 patients with OSA and 22 women with AHI &lt; 5 h−1, who were homogeneous in age, and body mass index (BMI). Women with OSA had significant higher levels of TNF-α, IL-1β, IL-8, and IL-10. We found significant correlations between AHI during REM and TNF-α (r = 0.40), IL-1β (r = 0.36), IL-6 (r = 0.52), IL-8 (r = 0.43), between obstructive apnea index and TNF-α (r = 0.46) and between AHI and IL-1β (r = 0.43). We also found that CT90% was related to IL-8 (r = 0.37). There were no significant differences in neonatal characteristics; however, we found inverse correlations between TNF-α and IL-8 with birth weight (both r = −0.48), while IL-8 showed a significant inverse relationship with neonatal gestational age (r = −0.48).Conclusions: OSA in our normal pregnancy population was associated with higher systemic inflammation, which was related to obstructive events, especially during REM sleep. Moreover, systemic inflammation was inversely correlated with neonatal birth weight and age.

Introduction: Vitamin D has known effects on the immune system, and its deficiency has been associated with allergen sensitization. Material and methods: A retrospective study was performed to evaluate the association between 25(OH)vitamin D (25(OH)D) and specific IgE for the most frequent allergens in our area in children and adolescents. All subjects under 15 years of age with a determination of Phadiatop ® or Phadiatop Infant ® and close serum 25(OH)D determination were included, from 2012 to 2019. From this sample, demographic and analytical variables were collected: specific IgE to Dermatophagoides pteronyssinus;dog and cat dander; grass, olive, and pellitory pollens; egg white; and cow milk; as well as complete blood count analysis and immunoglobulins.Results: A total of 749 subjects were recruited. Clusters according to deficiency, insufficiency, or sufficiency of 25(OH)D showed an association with age, Phadiatop ® , D. pteronyssinus, cat and dog dander specific IgE, and a higher frequency of positive allergen sensitization (P < .05). Logistic regression, compared with vitamin D levels of greater than 30 ng/mL after age adjustment, showed that deficient 25(OH)D was associated with D. pteronyssinus (OR 1.90; 95% CI, 1.25-2.90) and dog dander (OR, 2.10; 1.10-4.02); whereas insufficient 25(OH)D was associated with cat dander (OR, 2.46;) and also with D. pteronyssinus (OR, 1.55; 1.06-2.29) (P < .05). No associations were found between 25(OH) D levels and other analytical parameters. Conclusion:Vitamin D status is associated with sensitization to D. pteronyssinus, and cat and dog dander in children and adolescents, and also with a higher number of positive specific IgE.

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