The Absolute Basophil Count

TEMR: Trans-ethnic mendelian randomization method using large-scale GWAS summary datasets

Available large-scale genome-wide association study (GWAS) summary datasets predominantly stem from European populations, while sample sizes for other ethnicities, notably Central/South Asian, East Asian, African, Hispanic, etc., remain comparatively limited, resulting in low precision of causal effect estimations within these ethnicities when using Mendelian randomization (MR). In this paper, we propose a trans-ethnic MR method, TEMR, to improve the statistical power and estimation precision of MR in a target population that is underrepresented, using trans-ethnic large-scale GWAS summary datasets. TEMR incorporates trans-ethnic genetic correlation coefficients through a conditional likelihood-based inference framework, producing calibrated p values with substantially improved MR power. In the simulation study, compared with other existing MR methods, TEMR exhibited superior precision and statistical power in causal effect estimation within the target populations. Finally, we applied TEMR to infer causal relationships between concentrations of 16 blood biomarkers and the risk of developing five diseases (hypertension, ischemic stroke, type 2 diabetes, schizophrenia, and major depression disorder) in East Asian, African, and Hispanic/Latino populations, leveraging biobank-scale GWAS summary data obtained from individuals of European descent. We found that the causal biomarkers were mostly validated by previous MR methods, and we also discovered 17 causal relationships that were not identified using previously published MR methods.

Unveiling the influence of circulating immune cells count on type 1 diabetes: Insight from bidirectional Mendelian randomization

Observational studies have demonstrated an association between circulating immune cell and type 1 diabetes (T1D) risk. However, it is unknown whether this relationship is causal. Herein, we adopted a 2-sample bidirectional Mendelian randomization study to figure out whether circulating immune cell profiles causally impact T1D liability. Summary statistical data were obtained from genome-wide association study (GWAS) to investigate the causal relationship between white cell (WBC) count, 5 specific WBC count, and lymphocyte subtypes cell count and T1D risk. After false discovery rate (FDR) correction, the results indicated that lower lymphocyte cell count (odds ratio [OR] per 1 standard deviation [SD] decrease = 0.746, 95% confidence interval (CI): 0.673-0.828, PFDR = 0.036), and basophil cell count (OR per 1 SD decrease = 0.808, 95% CI: 0.700-0.932, PFDR = 0.010) were causally associated with T1D susceptibility. However, the absolute count of WBC, monocyte, neutrophil, eosinophil, and lymphocyte subtypes cell had no statistically significant effect on T1D risk. Taken together, this study indicates suggestive association between circulating immune cell count and T1D. Moreover, lower numbers of circulating lymphocyte and basophil cell were associated with the increased risk of T1D, which confirmed the immunity predisposition for T1D.

Analysis of Peripheral Blood Basophils in Pediatric Systemic Lupus Erythematosus

Basophils are the least abundant circulating leukocytes, and their immunological role has not yet been completely elucidated. There is evidence supporting their immunomodulatory role in several pathological settings; recently, studies in both experimental models and humans suggested that basophil homeostasis may be altered in systemic lupus erythematosus (SLE). Here, we first assessed circulating basophils in children affected with pediatric SLE (pSLE). In this cross-sectional study, circulating basophils were enumerated by fluorescence-based flow cytometry analysis in children affected with pSLE, in addition to children suffering from juvenile idiopathic arthritis (JIA) or non-inflammatory/non-rheumatic conditions. This study included 52 pediatric patients distributed in these three groups. We observed a statistically significant reduction of peripherally circulating basophils in children with pSLE compared to the other two groups of patients. This preliminary study is consistent with the available studies in adult patients with SLE showing a reduced number of circulating basophils. However, further research is needed to draw final conclusions on basophils' homeostasis in pSLE, in addition to their correlation with the disease activity and concomitant therapies.

Basophil counting in hematology analyzers: time to discontinue?

Basophils (basophilic granulocytes) are the least abundant cells in blood. Nowadays, basophils are included in the complete blood count performed by hematology analyzers and therefore reported in practically all patients in whom hematologic investigations are requested. However, hematology analyzers are not reliable enough to report clinically useful results. This is due to a combination of very high analytical imprecision and poor specificity, because the chemical and physical methods used for basophil counting in hematology analyzers are ill-defined and thus basophils are not well recognized by the analyzers. As a result, false basophil counts are quite common. In view of increasing analytical performance demands, hematology laboratories should stop reporting basophil counts produced by hematology analyzers. Suggestions for alternative pathways are presented for those situations where basophils are of clinical relevance.