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 (<10 ng/mL), deficient (≥10 ng/mL and <20 ng/mL), insufficient (≥20 ng/mL and <30 ng/mL), or sufficient (≥30 ng/mL). The mean/median eosinophil count in the four groups was 267/254 cells/μL, 245/238 cells/μL, 191/159 cells/μL, and 182/146 cells/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.