We examined the production of CD11b, CD62L and H2O2 by human peripheral blood granulocytes after treatment with soluble proteins prepared from five different pressure-disrupted strains of Staphylococcus aureus (SaSP) by flow cytometory. Peripheral blood was treated with final SaSP concentrations of 0.05, 0.5 and 5.0 micrograms for 20 min at 37 degrees C. The ratio of CD11b positive granulocytes did not increase at concentrations from 0.05 to 5.0 micrograms, but fluorescence intensity showed about two and three-fold increase, respectively, at concentrations of 0.5 and 5.0 micrograms, in comparison with that of control cells. The ratio CD62L positive cells decreased as follows: 0.5 microgram, 53.8% and 5.0 micrograms, 19.0%, respectively, whereas the control value was 79.8%. Fluorescence intensity also decreased as follows: 0.5 microgram, 10.4 and 5.0 micrograms, 9.2, respectively, whereas the control value was 46.8. Slight induction of H2O2 was found at 5.0 micrograms concentration only. In addition, SaSP treatment granulocytes that stimulated with PMA (1 ng) increased H2O2 production. Thus, SaSP has no beneficial effect against H2O2 production by granulocytes. All of the SaSP preparations indicated similar results for the production of CD11b, CD62L and H2O2 by granulocytes. SaSP effects activation of granulocytes, and the activation may occur independently of protein kinase C.