FIG. 2.

SHP-1 activity is downregulated in phagocytes infected with Opa₅₂-expressing N. gonorrhoeae. (A) The phosphatase activity of SHP-1 was significantly reduced in JOSK-M cells upon phagocytosis of Opa₅₂-expressing N. gonorrhoeae (N309) within 30 to 60 min, whereas infection with Opa⁻ P⁺ N. gonorrhoeae (N280) had no significant effect on SHP-1 activity. Cells were infected at an MOI of 50 and lysed at the indicated time points. Following SHP-1 immunoprecipitation, phosphatase activity was measured with NPP as substrate. Values are given as amounts relative to SHP-1 activity in unstimulated cells. Bars represent mean values of a representative experiment with triplicate samples. Overall significance was determined by one-way analysis of variance, and significance between samples was determined by the Tukey-Kramer multiple-comparison t test. Double asterisks indicate samples that are significantly (P < 0.01) different from the control. (B) Aliquots of SHP-1 immunoprecipitates (IP: α-SHP-1) used for in vitro phosphatase assays were separated by SDS-PAGE and employed in a Western blot with anti-SHP-1 antibodies (WB: α-SHP-1) to demonstrate equal amounts of precipitated enzyme in the samples. Control immunoprecipitates from cells infected with N309 for 30 min were obtained with isotype-matched control antibodies (30*).