Receptor-specific antibodies by immunization with "antisense" peptides?

Synthetic peptides whose sequences are specified by RNA complementary to the mRNA coding for peptide hormones have been reported to be useful antigens for the generation of receptor-specific antibodies. We have synthesized an eikositetrapeptide whose sequence corresponds to the complementary strand of the mRNA coding for the sequence of human ACTH(1-24). This "antisense" ACTH(1-24) peptide, "HTCAh," was coupled to bovine serum albumin or thyroglobulin prior to injection into rabbits. The complex proved to be very antigenic, inducing antisera of high titer and specificity. The antisera were tested in ACTH and MSH binding and bioassays, with or without prior purification of IgG molecules. None of the antisera displayed any effect in these assays, nor did they bind to blotted MSH/ACTH receptor protein from Cloudman S91 melanoma cells or to ACTH antibodies. The HTCAh peptide itself did not display measurable association to tritiated or iodinated ACTH(1-24), nor did it displace ACTH(1-24) in a receptor binding assay. However, the peptide bound to a low affinity site of mouse B16 melanoma cells which was independent of the MSH/ACTH binding site and induced melanin formation in these cells, but only at relatively high peptide concentration. Thus, in our hands, the antisense peptide approach using HTCAh as antigen did not lead to receptor-specific antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)