SDS-PAGE analysis of metabolically labeled rA3-C1 domains immunoprecipitated by LE and MV antibodies. The positive control was anti-A3 MoAb CLB-CAgA at saturating amounts (1 μg, lane 13), and the negative controls were ³⁵S-rA3-C1 with an anti-A2 antibody (lane 14) and without antibody (lane 15). Lanes 1 through 6 contain twofold dilutions from 1:60 to 1:1,920 of LE plasma, and lanes 7 through 12 dilutions 1:2 to 1:64 of MV plasma.