Influence of the SICCT on blood IL-10 responses. IL-10 responses were measured in blood samples from naturally infected cattle around the time of three consecutive SICCT tests (ST1–ST3). Blood samples were tested prior to (shaded bars) and at 3 (solid bars) and 10-days (unshaded bars) following each of three skin-tests (n = 15, 10 and 18 animals respectively). Data are presented as mean standardised IL-10 ELISA responses (U/mL) of PPD-B stimulated response minus the nil antigen response (± standard error). Where a response at either day 3 or 10 was significantly different from the pre-test response, this is indicated by **p < 0.01 or ***p < 0.001.