(1) Background: Vitamin D plays an important role in many types of cancer. It was the aim of this study to analyze serum 25-hydroxyvitamin D (25(OH)D) levels in newly diagnosed breast cancer patients, and the association with prognostic and lifestyle factors. (2) Methods: 110 non-metastatic breast cancer patients were included in the prospective observational “BEGYN” study at Saarland University Medical Center between September 2019 and January 2021. At the initiation visit, serum 25(OH)D levels were measured. Clinicopathological data on prognosis, nutrition, and lifestyle were extracted from data files and obtained using a questionnaire. (3) Results: Median serum 25(OH)D in breast cancer patients was 24 ng/mL (range 5–65 ng/mL), with 64.8% of patients being vitamin D deficient. 25(OH)D was higher among patients that reported the use of vitamin D supplements (43 ng/mL versus 22 ng/mL; p < 0.001), and in summer compared to other seasons (p = 0.03). Patients with moderate vitamin D deficiency were less likely to have triple negative breast cancer (p = 0.047). (4) Conclusions: Routinely measured vitamin D deficiency is common in breast cancer patients and needs to be detected and treated. However, our results do not support the hypothesis that vitamin D deficiency may be a main prognostic factor for breast cancer.

Background: The intrauterine and early extrauterine development represents a “window of opportunity” in the immunological development. The underlying mechanisms are still poorly understood. The aim of this study was to provide reference values B cell subpopulations in cord blood of term newborns, juveniles and in adults to find the spectrum of their physiological age-related variation. Methods: In this study, we used flow cytometry to evaluate human B lymphocytes and subpopulations in cord blood (n = 10), in peripheral blood from healthy juveniles aged 1 to 17 years (n=20) and from donors aged 24 to 62 years (n = 10). Results: Our findings showed increasing frequencies of IgM memory B cells, class-switched memory B cells, marginal zone B cells and plasmablasts, from cord blood to peripheral blood of juveniles and adults. In con-trast, the percentage of naïve B cells was higher in newborns than in juveniles and adults. The frequencies of were similar in cord blood and peripheral blood of adults. Interestingly, transitional B cells frequencies were similar in cord blood and adults but significantly lower in juveniles. Conclusions: The frequencies of circulating B cell subpopulation are subject to considerable changes during on-togeny, reflecting overlying effects of maturation and of the acquisition of an adaptive immune memory.

Background The intrauterine and early extrauterine development represents a “window of opportunity” in the immuno-logical development. The underlying mechanisms are still poorly understood. The aim of this study was to provide reference values B cell subpopulations in cord blood of term newborns, juveniles and in adults to find the spectrum of their physiological age-related variation. Methods In this study, we used flow cytometry to evaluate human B lymphocytes and subpopulations in cord blood (n = 10), in peripheral blood from healthy juveniles aged 1 to 17 years (n = 20) and from donors aged 24 to 62 years (n = 10). Results Our findings showed increasing frequencies of IgM memory B cells, class-switched memory B cells, marginal zone B cells and plasmablasts, from cord blood to peripheral blood of juveniles and adults. In contrast, the percentage of naïve B cells was higher in newborns than in juveniles and adults. The frequencies of immature B cells were similar were similar in cord blood and peripheral blood of adults. Interestingly, transitional B cells frequencies were similar in cord blood and adults but significantly lower in juveniles. Conclusions The frequencies of circulating B cell subpopulation are subject to considerable changes during ontogeny, reflecting overlying effects of maturation and of the acquisition of an adaptive immune memory.