Digitalis inhibits and furosemide does not change the in vitro phagocytic function of neutrophils of healthy subjects.

This work evaluated the in vitro influence of digitalis and furosemide on the phagocytic function of neutrophils of healthy individuals. Phagocytosis of Saccharomyces cerevisiae by peripheral blood neutrophils of 20 healthy individuals was assessed in the absence or presence of deslanoside or furosemide. The Wilcoxon test was employed to compare the data expressed as median and extreme values. Digitalis reduced the number of yeasts ingested by neutrophils (2.23, 1.23-4.01 versus 1.89, 0.87-2.79; p = 0.019). It did not influence the percentage of these cells engaged in phagocytosis, although there was a tendency for reduction (71%, 23-95% versus 57%, 8-93%; p = 0.11), which resulted in decreasing the phagocytic index from 192 (30-381) to 125 (10-218) (p = 0.028). Furosemide had no significant influence on the number of S. cerevisiae phagocytosed (2.23, 1.23-4.01 versus 1.96, 0.70-4.45; p = 0.89), the percent of phagocytosing neutrophils (71%, 23-95% versus 73%, 9-96%; p = 0.86) and the phagocytic index (192, 30-381 versus 152, 10-428; p = 0.95). These findings indicate the inhibitory influence of digitalis on in vitro neutrophil phagocytic function of healthy subjects, and suggest that this effect might impair the innate immune defense response. On this basis, they could contribute to improve digitalis therapy and advise that this drug class should not be associated with other drugs that may also impair the immune function, or might be used with caution or even avoided in subjects with infections.