ANTIGENIC EPITOPES ON BETA(2)-MICROGLOBULIN REACTING WITH MONOCLONAL-ANTIBODIES

Monoclonol antibody-reactive antigenic regions on the 99 amino acid se quence of human beta2-microglobulin were examined by using nine anti-b eta2M monoclonal antibodies (Mabs) and Geysen pins coated with overlap ping heptamers derived from the primary sequence. Reactive linear sequ ences were then restudied with glycine substitution for each successiv e residue. All nine mAbs showed a similar profile, with peak reactivit y at residues 57-63 SKDWSFY and 87-97 LSQPKIVKWDR. Glycine substitutio n established the tryptophons at positions 60 and 95 as well os the ly sines at 58, 91, and 94 as immunodominant residues important for mAb r eactivity. Other adjacent residues (serine 57, phenylolonine 62, tyros ine 63, isoleucine 92, valine 93, and proline 90) also make important contributions to beta2M antigenic epitopes. Rabbit antipeptide antibod ies against the beta2M peptides SKDWSFY and LSQPKIVKWDR produced quant itative precipitin curves with beta2M in solution. Addition of iodine 125-labeled beta2M to antipeptide antibody followed by protein A preci pitation and sodium dodecyl sulfate gel electrophoresis with autoradio graphy showed that labeled beta2m reacted in solution phase with anti- SKDWSFY or anti-LSQPKIVKWDR antibody. These findings establish residue s 57-63 and 87-97 in human beta2M as major reactive antigenic sites fo r monoclonal as well as polyclonal anti-beta2m antibodies.