(A) Evaluation of the purities of different ch14.18-IL-2
fusion protein preparations by SDS-PAGE. Lane 1, molecular size markers
(94, 67, 43, 30, and 20 kDa); lane 2, purified ch14.18; lane 3,
ch14.18-IL-2 (lot 1); lane 4, ch14.18-IL-2 (lot 31403); lane 5,
lower-molecular-weight derivative of the ch14.18-IL-2 fusion protein
(an aliquot from a partially purified batch of ch14.18-IL-2 that had
been obtained from a cell line which was maintained in the presence of
fetal calf serum). (B) Western blot analysis with anti-human IgG1
antibody conjugated with horseradish peroxidase. Lane 1, purified
ch14.18; lane 2, ch14.18-IL-2 (lot 1); lane 3, ch14.18-IL-2 (lot
31403); lane 4, lower-molecular-weight derivative of the ch14.18-IL-2
fusion protein.