Effect of amoxycillin and doxycycline on function of human granulocytes tested in vitro and on chemotaxis of granulocytes from rabbits given the two antibiotics.

The effect of amoxycillin and doxycycline on human granulocyte function was studied in vitro. The antimicrobial agents were added to tests of chemotaxis, random motility, yeast phagocytosis, and killing, at progressing concentrations. The effect was also evaluated in vivo by measuring chemotaxis and random motility (agarose technique) of granulocytes from rabbits injected with these antibiotics. Amoxycillin was shown to have a slightly stimulating effect on chemotaxis, demonstrable only at the highest concentration tested (100 micrograms/ml), and no effect on the other variables. Doxycycline had a dose-related inhibitory effect on chemotaxis, random motility, and phagocytosis, and no effect on killing. Chemotaxis and random motility were slightly, but not significantly, stimulated in vivo when rabbits were given amoxycillin. Chemotaxis (but not random motility) was significantly impaired when the rabbits were given doxycycline.