Measurement of IFN-γ, IL-10, IL-12, IL-1, TNF-α and MIP-1β using a multiplex luminescence assay. Blood was collected from cattle naturally infected with M. bovis (n = 23) immediately prior to each of three successive skin-tests (ST1–ST3). PPD-B stimulated responses in whole blood cultures are presented at each time-point as the mean value (± standard error) with the no-antigen control response subtracted. TNF-α data is presented in units of luminescence whilst all other responses are calibrated against a recombinant standard that was run on each assay plate. Significance between ST1 and subsequent readings is indicated by *(p < 0.05).