Cytokine concentrations and responses measured by a commercial MMIA.

Median background cytokine concentrations (Nil, pg/mL) and cytokine responses (pg/mL) to phytohemagglutinin (Mitogen Response) and to a combination of early secreted antigenic target-6, culture filtrate protein 10, and TB7.7 (ESAT-6+CFP-10+TB7.7 Response) are listed with ranges in parentheses. Cytokine concentrations were measured with a custom commercial multiplexed microsphere-based immunoassay (commercial MMIA) for patients with culture-confirmed tuberculosis (patients) and subjects at low risk for M. tuberculosis (Mtb) infection (controls). For values that were designated “out of range” by Bio-Plex Manager software, low values are reported as 0 and high values are reported as the observed value of the highest standard concentration multiplied by the dilution factor. Responses were calculated by subtracting the background cytokine concentration in plasma from blood incubated with saline (Nil) from the cytokine concentration in plasma from blood incubated with mitogen or Mtb antigen. N = 12 for patients and N = 12 for controls. P values were calculated by Mann-Whitney U Rank Sum test comparing cytokine concentrations or responses for patients versus controls. Significant differences (pbold type.