LHRH diacetate tetrahydrate was conjugated to potato acid phosphatase and an emulsion composed of the conjugate and Freunds complete adjuvant was injected into the hind limb of female CAF1 mice. Immune spleen cells were fused with P3-X63-Ag8.653/3 myeloma cells by a modification of the original cell fusion method using polyethylene glycol. A hybridoma screening assays were used to select for high affinity monoclonal antibodies.