Reaginic (type 1 anaphylactic) antibodies produced by calves in response to Hypoderma larvae

Reaginic antibody production by Hypoderma lineatum and H bovis larval antigens were evaluated in three calves using passive cutaneous anaphylaxis (PCA). Two calves were sensitised with soluble extract of H lineatum larvae and a third was injected with 43 hatching H bovis larvae. Blood serum taken from the calves was injected intradermally in 0.1 ml volumes into three test calves. Sera from the calves sensitised with hypoderma extract produced positive PCA reactions in all three calves with maximum titres of 1:8. Sera from the calf injected with living larvae caused positive PCA reactions in two of the three test calves, the maximum titre being 1:4. The results indicate that the calves produced reaginic antibody to H bovis and H lineatum, although serum concentrations of the antibody were relatively low.