Influence of tetracyclines and light on the release of lysozyme from human granulocytes and monocytes

Doxycycline inhibited the release of lysozyme from human granulocytes and monocytes exposed to non-opsonized zymosan particles. This effect was more marked for granulocytes than for monocytes. Oxytetracycline, however, did not influence the release. The difference between the drugs can be explained by differences in their lipid solubilities. The divalent cation chelator, EDTA, also reduced the release of lysozyme from leukocytes exposed to non-opsonized zymosan. Accordingly, the selective release of lysozyme from human leukocytes is divalent cation dependent. The inhibition of release by doxycycline is most likely also due to binding of these ions. When the cells were exposed to UVA light in the presence of doxycycline, the inhibition of lysozyme release was potentiated. Using irradiated cells, maximal inhibition was obtained at 20 micrograms doxycycline/ml. However, it is not clear whether these results have clinical relevance.