Mouse F(ab')2 IgG1 Lambda Isotype Control Antibody [SPRD]

This investigation describes the detection of a component in Escherichia coli capable of binding a large proportion of human antibody variable domains including otherwise highly monospecific antibodies induced by an in vivo antibody response. This interaction is of low affinity, but cross-linking of IgG molecules by, e.g. anti-immunoglobulin preparations, provides a sufficient degree of multivalency to promote a high avidity interaction. This binding which occurs both with kappa and lambda light chain-containing antibodies, appears to involve the variable region of human antibodies making it a superantigen-like activity. This is proposed based on the facts that: (i) different human antibodies of IgG1 isotype appear to bind to different extents suggesting that variable domain differences determine the binding activity; and (ii) addition of soluble antigen abrogates the interaction with the E. coli-derived molecule. Future studies of the nature and possible in vivo consequences of these interactions are warranted since any superantigen activity associated with this binding might affect the human immune response occurring as a consequence of E. coli infections.

We previously demonstrated that D-amino acids can form as a result of photo-irradiation of a monoclonal antibody (mAb) at both lambda = 254 nm and lambda > 295 nm (lambda(max) = 305 nm), likely via reversible hydrogen transfer reactions of intermediary thiyl radicals. Here, we investigate the role of various excipients (sucrose, glucose, L-Arg, L-Met and L-Leu) on D-amino acid formation, and specifically the distribution of D-amino acids in mAb monomers and aggregates present after light exposure. The mAb-containing formulations were photo-irradiated at lambda = 254 nm and lambda(max) = 305 nm, followed by fractionation of aggregate and monomer fractions using size exclusion chromatography. These aggregate and monomer fractions were subjected to hydrolysis and subsequent amino acid analysis. Both aggregate and monomer fractions collected from all formulations showed the formation of D-Glu and D-Val, whereas the formation of D-Ala was limited to the aggregate fraction collected from an L-Arg-containing formulation. Interestingly, quantitative analysis revealed higher yields of D-amino acids in the L-Arg-containing formulation. Generally, D-amino acids accumulated to similar extents in monomers and aggregates.