Keyhole limpet hemocyanin (KLH)--a potent antigen in reaginic sensitization of mice and rats; a comparison with egg albumin (EA)-induced reaction.

Two distinct antigenic functions of KLH and EA were tested in four inbred strains of mice (BALB/c, 129, C3H/A, C57BL/6J:a) stimulation of reaginic antibody production after subcutaneous introduction of antigen in alum-precipitated form, and b) ability to elicit an anaphylactic reaction in vitro on pre-sensitized peritoneal mast cells. KLH was found to be more effective than EA in both functions tested, inducing higher titres of IgE and IgG1 antibody levels in the sera as well as higher percentage of histamine release from actively and passively sensitized peritoneal mast cells. Two different forms of KLH (associated and dissociated) were tested for potency in stimulating an anaphylactic sensitization of mice and rats and capacity to elicit an anaphylactic reaction on their peritoneal mast cells in vitro. In all rats as well as in BALB/c, 129 and C3H/A mice sensitization with dissociated KLH resulted in higher percentage of antigen-induced histamine release from peritoneal mast cells (an exception: mast cells of C57CL/6J mice released a little more histamine on the challenge with associated KLH). The PCA tests show, that the dissociated KLH does not act through greater stimulation of antibody formation.