Impact of vitamin D deficiency on increased blood eosinophil counts.

OBJECTIVE/BACKGROUND: Vitamin D has been increasingly recognized as an immunomodulatory agent. Its deficiency has been associated with immune-mediated diseases such as asthma, rhinitis, and atopic dermatitis. These allergic conditions are dependent on T-helper type 2 (Th2) cells secreting interleukins, overproduction of immunoglobulin E (IgE), and eosinophil activation. We investigated the association between serum vitamin D levels and blood absolute eosinophil count.

METHODS: We carried out a cross-sectional study of 669 men and women referred to a clinical pathology laboratory who underwent 25-hydroxyvitamin D testing and complete blood count analysis on the same day.

RESULTS: Vitamin D levels were stratified into four ranges: severely deficient (<10ng/mL), deficient (≥10ng/mL and <20ng/mL), insufficient (≥20ng/mL and <30ng/mL), or sufficient (≥30ng/mL). The mean/median eosinophil count in the four groups was 267/254cells/μL, 245/238cells/μL, 191/159cells/μL, and 182/146cells/μL, respectively, (p=.001). The difference was significant between the severe deficiency group and each of the other three groups (p=.012, p=.002, and p=.001, respectively). There was no statistical difference among the four groups in terms of total leukocyte counts (p=.151), neutrophils (p=.177), or lymphocytes (p=.582).

CONCLUSION: Vitamin D deficiency was associated with higher blood eosinophil count. These results support the possible role of vitamin D in the eosinophil immune response.