Human IgG1 Lambda Isotype Control Antibody [HRP]

Structural similarities between two members of the immunoglobulin superfamily were explored by making chimeric immunoglobulin/CD4 antigen molecules. A crossover in the middle of the originally proposed J(k) homology unit of the first domain of the CD4 molecule was used to construct a chimeric molecule having human and mouse CD4 antigen sequence through the first 108 amino acids and murine J(k) and C(k) sequence thereafter. This molecule was expressed in the presence and absence of an immunoglobulin heavy chain. The resulting proteins were assayed for the expression of CD4 epitopes that should be present based on epitope mapping data. Monomeric, homodimeric, and heavy chain/light chain tetrameric forms of the recombinant protein were secreted and were all detectable with anti-kappa reagents. CD4 antibodies precipitated only the form of the CD4-C(k) light chain protein which appears as a monomer by polyacrylamide gel electrophoresis. Neither the homodimer nor the heavy chain/light chain tetramer were detected with CD4 monoclonal antibodies. An engineered gene having this CD4 antigen first domain joined to the human IgG1 constant region, when coexpressed with a mouse lambda light chain, also failed to express detectable CD4 epitopes. The structural implications of the presence or absence of CD4 epitopes on these proteins is discussed.

Mouse hybridomas were generated by electrofusing SP2/0-Ag14 myeloma cells with lymphocytes of BALB/c mice immunized with Newcastle disease virus (NDV) strain AF2240. From the 15 hybridomas clones that were established, 13 clones produced sub-class IgG1 and lambda light chain monoclonal antibodies (Mabs) while two clones produced Mabs of the sub-class IgG3 and kappa light chain type. The Mabs reacted to three strains of NDV representing two different pathotypes but none showed neutralization activity. Five of the Mabs were specific to the 12.5 kD F2 fragment of the viral fusion protein. Two clones were capable of growing and secreting Mabs in serum-free medium supplemented with insulin, transferrin, ethanolamine and selenium (ITES).