Comparison of MCP-2 production upon challenge with either F62ΔlgtD or sialylated F62ΔlgtD. Primary human monocytes (1 × 106/ml) were challenged with gentamicin-killed gonococci (1 × 107/ml) for 18 hours prior to analysis of sample supernatants using a protein array to detect the presence of cytokines. Densitometric analysis was carried out using a Gel Doc 2000 camera and Quantity One Software (BioRad Laboratories, Inc.). Analysis of internal positive controls (+) among array exposures using a paired, two-tailed, t test with a 95% confidence interval indicated that the means were statistically similar (P > 0.05), allowing cross comparison of sample cytokine levels. (A) Whole array for each sample: (-) negative control, F62ΔlgtD, and F62ΔlgtD (S) Dashed boxes indicate the location of MCP-2 antibodies spotted on the array membrane. (B) Internal positive controls compared with MCP-2. Data shown are from one experiment. (S) Indicates sialylated samples.