Production of a diagnostic monoclonal antibody in perennial alfalfa plants

The increasing use of monoclonal antibodies (mAbs) in diagnostic reagents n ecessitates efficient and cost-effective mAb production methods. In blood b anks, one of the most routinely used reagents is the antihuman IgG reagent used for the detection of nonagglutinating antibodies. Here we report the p roduction of a functional, purified anti-human IgG, through the expression of its encoding genes in perennial transgenic alfalfa. Transgenic plants ex pressing the light- and heavy-chain encoding mRNAs were obtained, and plant s from crosses were found to express fully assembled C5-1. The purification procedure yielded mainly the H2L2 form with specificity and affinity ident ical to those of hybridoma-derived C5-1. The ability to accumulate the anti body was maintained both in parental F1 lines during repeated harvesting an d in clonal material; the antibody was stable in the drying hay as in extra cts made in pure water. Also, plant and hybridoma-derived C5-1 had similar in vivo half-lives in mice. These results indicate that plant C5-1 could be used in a diagnostic reagent as effectively as hybridoma-derived C5-1, and demonstrates the usefulness of perennial systems for the cost-effective, s table, and reliable production of large amounts of mAbs. (C) 1999 John Wile y & Sons, Inc.