Development of a quantitative cell-based ELISA, for a humanized anti-IL-2/IL-15 receptor beta antibody (HuMikbeta(1)), and correlation with functional activity using an antigen-transfected murine cell line.
The HuMikbeta(1), a humanized IgG1 monoclonal antibody directed toward the IL-2/IL-15 receptor beta-chain (CD122), inhibits the actions of the inflammatory cytokine IL-15, and may be useful for immunotherapy of an array of autoimmune disorders as well as diseases associated with the retrovirus human T-cell lymphotrophic virus 1 (HTLV-1). In order to facilitate the production of material for clinical investigation, we developed a cell-based ELISA (CbELISA) for measuring the binding activity, as a potential biological activity marker, of the HuMikbeta(1) monoclonal antibody to a transfected 32D mouse cell line (32Dbeta) expressing IL-2Rbeta antigen on the cell surface. There is specific binding of HuMikbeta(1) to the transfected cell line, titrating out in the concentration range of 1-1,000 ng/ml. Under identical conditions, there was no binding of HuMikbeta(1) to the parent cell line 32D. Satisfactory binding curves with HuMikbeta(1) were obtained with 32Dbeta cells grown between 3 and 19 passages in culture and at seed densities of 2 x 10(5)-4 x 10(6) cells/well. The binding was specific for Mikbeta antibodies recognizing the IL-2/IL-15 receptor beta subunit as demonstrated by binding of HuMikbeta(1), Mikbeta(2) and Mikbeta(3) antibodies, and lack of binding of irrelevant humanized and chimeric antibodies and isotype-matched human IgG1 to the 32Dbeta cell. Also, the human IgG1 and irrelevant humanized and chimeric antibodies did not interfere with the HuMikbeta(1) binding. The assay could detect changes in binding activity of HuMikbeta(1) antibody under stressful conditions (heat and low pH) and the results paralleled the effect of stress on the physicochemical characteristics. More importantly, the binding activity shows an apparent correlation to inhibition of IL-15-induced proliferation of 32Dbeta cells with HuMikbeta(1). In conclusion, the cell-based ELISA method represents a simple, reproducible accurate quantitative assay for monitoring HuMikbeta(1) activity and could be used as a potency marker assay for monitoring the lot-lot consistency and functional stability of HuMikbeta(1) product.
Bioanalytical Development Laboratory, Biopharmaceutical Development Program, SAIC Frederick Inc., NCI-Frederick, FortDetrick, Frederick, MD 21702, USA.
Xiao Yi
XY
Yang
Eying
E
Chen
Hengguang
H
Jiang
Wanda K
WK
Hartmann
Gautam
G
Mitra
Toby
T
Hecht
Gopalan
G
Soman
D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis*; D049109:Cell Proliferation; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D018664:Interleukin-12 / Q000276:immunology*; D019169:Jurkat Cells; D051379:Mice; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D014162:Transfection
D000911:Antibodies, Monoclonal; C508024:IL15RA protein, human; C508025:Il15ra protein, mouse; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2; D018664:Interleukin-12