BACKGROUND: Nicotinic acid and nonivamide are often applied topically during capillary blood collection to induce vasodilation. These molecules may have an influence on immune effector cell activity in nearby tissues. This study investigates whether the induction of flushing by nicotinic acid and nonivamide causes an inflammatory response that influences the composition of immune cells present in a capillary blood sample.
METHODS: Females aged between 18 and 30 years old provided capillary blood samples. Experimental samples were taken from an earlobe treated with nicotinic acid and nonivamide with controls obtained from the untreated earlobe. Immunophenotypic analyses were conducted using polychromatic flow cytometry to determine whether any changes occurred in leucocyte subpopulations (CD3, CD4, CD8, CD19, CD56, and CD14) and granulocytic functional-related surface antigen markers (CD11b, CD18, CD16b, and CD66b).
RESULTS: No significant differences were observed between experimental and control samples in the mean percent of parent for the lymphocyte, monocyte, or granulocyte subpopulations, or in the median fluorescence intensity of particular surface markers expressed on these leucocytes.
CONCLUSION: The topical application of nicotinic acid and nonivamide is a possible method to improve capillary blood collection for immunological assessments. The use of these agents may increase the safety and compliance of patients who suffer from needle phobia or are unable to provide venous blood samples.