BackgroundSubcutaneous Immunotherapy (SCIT) modifies the allergic response and relieves allergic symptoms. SCIT is the only and a very effective treatment for insect venom allergy. We hypothesized that basophil sensitivity, measured through the basophil activation test, would decrease during SCIT up dosing. Expression of CD203c was compared to CD63 as marker for basophil activation, using a Bland Altman plot and ROC curves.MethodsPatients (n = 18) starting subcutaneous SCIT for wasp allergy with an up dosing scheme of 7 to 11 weeks were enrolled. Heparinised blood samples were drawn at weeks 1-4, 7 and at the first maintenance visit. Basophils were stimulated at 7 log dilutions of V. vespula allergen for 15 min, and were stained with CD203c and CD63. Basophils were identified as CD203c+ leukocytes, and the proportion of CD63+ and CD203c+ cells were plotted against allergen concentration. A sigmoid curve was fitted to the points, and the allergen concentration at which half of the maximal activation was achieved, LC50, was calculated. In another series of experiments, LC50 calculated in whole blood (AP) was subtracted from LC50 calculated with basophils suspended in plasma from a nonatopic donor (HS) to determine the protective effect of soluble factors in blood of patients treated with SCIT.ResultsHeparin blood basophil activation was similar through CD63 and CD203c. Basophils were significantly more sensitized three weeks after initiation of SCIT compared to baseline (p < 0,01). The difference in LC50 increased by 1,04 LC50 units (p = 0,04) in patients that had just achieved maintenance dose compared with patients before initiating SCIT. When maintenance allergen concentrations had been reached, an increase in the protective plasma component was documented. Blood basophil concentration was marginally reduced by SCIT.ConclusionBasophil activation is a versatile and sensitive tool that measures changes in the humoral immune response to allergen during SCIT.

Despite the presumption of a beneficial effect of magnesium (Mg) supplementation on various diseases, little is known concerning the pharmacokinetics of Mg hydroxide. This study was designed to provide a pharmacokinetic profile of Mg hydroxide after a single oral dose. Ten healthy male adults participated in this cross-over study with three 24-hr study days. Interventions were (i) none (baseline), (ii) oral intake of three (3 × 360 mg) tablets of Mg hydroxide (Mablet ) and (iii) IV bolus infusion of 2 g Mg sulphate (index drug). Blood samples were collected before the single dose, after (i.e. after treatment administration) 15, 30, 60, 90 and 120 min. and after 3, 4, 6, 8, 12 and 24 hr. Urine was collected in four 6-hr periods per study day. Blood (N = 10) and urine (N = 6) Mg were analysed by descriptive statistics. Bioavailability was 14.9% (CI: 8.3; 26.8), blood clearance was 5.1 L/hr (CI: 2.1; 17.0), apparent volume of distribution was 60.2 L (CI: 35.6; 102.0), elimination constant was 0.08 per hour (CI: 0.05; 0.14), half-life was 8.3 hr (CI: 4.8; 14.1), C was 0.11 mmol/L (CI: 0.07; 0.14), and AUC was 92.3 mmol/L × min. (CI: 45.5; 139.1). Urine Mg excretion augmented by 17.7% (CI: 8.9; 35.0) from baseline. No severe side effects were observed. The bioavailability of Mg hydroxide was 15%, and it constitutes a clinically relevant option for oral Mg supplementation. No severe side effects were seen.

Serum levels of vitD, Mg and Ca were not related to FEV1. Most participants in this study were vitD-, Mg- and Ca sufficient. Women had higher se vitD than men. Se Mg, but not se vitD and se Ca, was associated with QoL in COPD. Prospective randomized studies are needed to substantiate these finding. Clinical trials ID at www.clinicaltrials.gov: NCT01564953.

Thank you to Dr. Rutten for the comment on our manuscript "Serum magnesium and not vitamin D is associated with better QoL in COPD: A cross-sectional study". Dr. Rutten mentions that effects of a nutrient will only be visual in case of deficiency, and once sufficient, there is no additional benefits of the nutrient. In our study, most participants were serum vitamin D, magnesium and calcium sufficient, and few were nutrient deficient based on serum values. In the manuscript we have mentioned, that based on the small group with subnormal serum magnesium and the lack of participants with very low serum vitamin D, our results cannot rule out an association between lung function and serum vitamin D or serum magnesium in patients with deficiency of the given nutrient. Concerning the use of univariate correlations to show the relationships between nutrients and lung function or QoL without correction for other factors, we have explained that serum vitamin D was measured as 25-(OH)-D3 as it reflects the concentration of both sunlight-induced synthesis and intake of vitamin D in the previous 3e4 weeks. We also measured ionised calcium and serum magnesium. We did not correct for other factors as the measurements of these nutrients were defined separately. Lung function was measured as FEV1 in % predicted, and participants were recruited during summer time to minimize possible seasonal variation of both vitamin D and risk of exacerbations. As this study is a cross-sectional and not a longitudinal intervention study, we cannot evaluate a relationship between the parameters and health outcome over time.