A. Osteoclasts were generated as described in the Materials and Methods section for 17 days. Osteoclasts were then left untreated or treated with ZOL at 500 nM or 5 μM. After 4 days of treatment, surface expression of CD54, MHC-I, MHC-II, CD44, CD14, CD11b and B7H1 were determined using flow cytometric analysis after staining with the respective PE-conjugated antibodies B. Osteoclasts were left untreated or treated with ZOL (1 μM) or supernatants harvested from pre-activated NK cells cultured with monocytes and probiotic bacteria (sAJ2) for 48 hours. Surface expressions of CD54, MHC-I, MHC-II, CD44, CD14 and CD11b were determined using flow cytometric analysis after staining with the respective PE-conjugated antibodies C. Isotype control antibodies were used as control. The numbers on the right hand corner are the percentages and the mean channel fluoresence intensities for each histogram.