Systemic IgE, IgG
, IgA and total Ig antibody reactivities to HDM extract, Der p 1 and Der p 2 in serum from control and HDM-immunized sheep. Peripheral blood serum samples were collected before (open bars) and 7 days after (closed bars) the final HDM injection, with time-matched serum samples also collected from control animals. In each of the plots, ELISA data is presented as mean absorbance values Â± s.d. * indicates significant differences (p < 0.05) comparing samples collected before and after HDM exposure; n = 3â€“4 per group.