FAST IMMUNOPURIFICATION OF SMALL AMOUNTS OF SPECIFIC ANTIBODIES ON PEPTIDES BOUND TO ELISA PLATES

ELISA is widely used as a means to detect 'antibodies, but the potenti al of ELISA plates as an immunosorbent for the purification of specifi c antibodies does not seem to have been evaluated. In this study, ELIS A plates coated with peptides representing short sequences of various antigens from Plasmodium falciparum, the etiologic agent of human mala ria, have been successfully used as a means to purify small amounts of the corresponding antibodies. ELISA plates, identical to those used f or antibody detection, also permitted the evaluation of various elutio n conditions for each pairing of peptide and serum; we tested four elu ting buffers (0.2 M glycine, pH 2.5; 0.2 M lysine, pH 11.5; 3.0 M MgCl 2, 0.075 M Hepes, 25% ethylene glycol, pH 7.1-7.2 and 4 M NH4SCN in 0. 1 M NaH2PO4, pH 6.0) with four pairs of peptides and sera. The ELISA p lates could also be used to estimate the affinity of the eluted antibo dies by the technique of Pullen et al. (1986). The eluted antibodies w ere compared to those obtained by immunopurification on recombinant pr oteins adsorbed on nitrocellulose filters. In contrast to the latter, they were not contaminated by antibodies directed against the carrier moiety of the recombinant protein. When used in immunofluorescence ass ays with various stages of the parasite the antibodies immunopurified on peptides bound to ELISA plates were able to react with the native a ntigens in the parasite.