Origin of the Isoelectric Heterogeneity of Monoclonal Immunoglobulin h1B4

摘要: The origin of the microheterogeneity a highly purified antiinflammatory humanized monoclonal antibody prepared in mammalian cell culture has been investigated. This is an IgG directed toward human CD 18 (a subunit leukocyte integrins). When preparation subjected to isoelectric focusing, it found contain four major species with pI values ranging from 6 7. Although relative amounts each form differ and some are present only small quantities, isolated by combination high-resolution anion-exchange chromatography focusing. Comparative studies reveal no detectable differences overall secondary (far UV circular dichroism) or tertiary (intrinsic fluorescence) structure, molecular weight (laser-desorption mass spectroscopy), antigen binding activity. incubated under conditions which favor deamidation, converted forms lower appear correspond naturally observed species. While light chain relatively homogeneous, heavy exhibits pattern focusing bands similar that intact immunoglobulin. These results suggest this case, charge due sequential deamidation immunoglobulin chain.