Kathryn E. Stein
Center for Biologics Evaluation and Research
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Publication
Featured researches published by Kathryn E. Stein.
Journal of Immunology | 2000
Subramanian Muthukkumar; Julia Goldstein; Kathryn E. Stein
The immune response to polysaccharide (PS) Ags in mice is delayed during ontogeny even when administered in a thymus-dependent (TD) form. In this study, Neisseria meningitidis group C PS-tetanus toxoid conjugate (MCPS-TT) vaccine was used to examine whether the delay in the development of Ab responses to TD PS conjugate vaccines in neonatal mice is due to defective Ag presentation. The results show that B cells and dendritic cells (DC) from 3- and 7-day-old mice were severely defective in presenting TT and MCPS-TT to Ag-specific T cell clones. The ability of these cells to present Ag reaches adult levels by 4 wk. The development of anti-MCPS and anti-TT Abs in neonatal mice parallels the functional ability of their APC to present Ag. DC from neonatal mice expressed very low levels of MHC class II, costimulatory molecules B7.1, B7.2, and CD11c but high levels of monocyte-specific markers F4/80 and CD11b and granulocyte marker, Ly6G. Significant changes in the expression of these markers were observed as the age of the mice increased. MHC class II, B7.1 and B7.2, and CD11c all increased with age, reaching adult levels between 3 and 4 wk, concurrent with the function of APC. These results demonstrate that one reason neonates fail to produce high titers of anti-PS Abs even when immunized in a TD form is that their B cells and DC are not fully functional.
Journal of Chromatography A | 2003
Kurt Brorson; Janice Brown; Elizabeth Hamilton; Kathryn E. Stein
A potential safety concern in biotechnology purification schemes that employ re-use of column media, often for large numbers of chromatography runs, is loss of the virus removal capacity of the chromatographic purification operation over time. To define chromatography performance attributes that best predict retrovirus clearance during extended re-use of protein A media, small-scale protein A columns were cycled 150 to 460 times using concentrates of murine hybridoma cell culture supernatants, standard low pH elution buffers and different cleaning solutions (6 M urea, 6 M guanidine, 100 mM NaOH or 500 mM NaOH). Load, flow-through and eluate samples were taken periodically and assayed for reverse transcriptase (RT, an enzyme component of retroviruses) activity, bovine IgG (a component of the culture media), genomic DNA, leached protein A, and mouse IgG. Under all cleaning conditions tested, the log,10 reduction value (LRV) of RT activity did not decrease and impurity co-elution did not increase during the 150 to 460 purification/cleaning cycles. In the two studies in which the columns were cleaned with NaOH, the chromatography performance attribute that best predicted the column media lifespan was column capacity, as measured by antibody (Ab) step yield and breakthrough. In both studies, Ab capture decayed in a biphasic manner starting at cycle 200 (100 mM NaOH) or cycle 50 (500 mM NaOH). For media cycled 300+ times using 6 M urea or 6 M guanidine cleaning buffers, column performance, including RT activity LRV, was more stable, although small upward trends in Ab breakthrough were evident. In summary, our studies identify Ab step yield and breakthrough as performance attributes that decay prior to retrovirus LRV when protein A media is multiply-cycled. Thus, we propose that virus removal validation studies should be performed on new media only and these attributes can be monitored during protein A unit operations in lieu of performing virus removal validation studies with cycled protein A media.
Current Opinion in Biotechnology | 2001
Kathryn E. Stein; Keith O Webber
Recently, there has been a large increase in the number and types of biological products--from therapeutic antibodies to vaccines for the prevention of infectious diseases--that are produced in bioengineered plant systems. We anticipate that this technology will be used increasingly on a commercial scale for the manufacture of human and animal products. These production systems have the capacity to produce very large quantities of products at lower costs and with reduced risks compared with mammalian systems.
Trends in Biotechnology | 1997
Kathryn E. Stein
Using current monoclonal antibody technology one can now produce a humanized antibody to virtually any target antigen that can be identified. Consequently, one would expect there to be more approved monoclonal antibody products. Inadequate product development at both the preclinical and clinical stages has contributed to the overall lack of success. This article discusses some of the obstacles to successful product development and offers suggestions to overcoming them. The key to monoclonal antibody development, as with other biological products, is understanding the properties of the product itself, to have some proof of concept before embarking on clinical studies, and to adequately design and power the pivotal trial.
Molecular Immunology | 1995
Kurt Brorson; Michael V. Krasnokutsky; Kathryn E. Stein
Mice with the x-linked immunodeficiency mutation (xid) are unresponsive to polysaccharide antigens, lack a subset of B cells, and have low serum IgM (2-20% of normal) and IgG3 (3% of normal). Because of the disproportionate reduction of IgG3, the ability of B cells from xid mice to switch to gamma 3 was examined. Switching was indirectly measured by comparing IgG3 production and C gamma 3 mRNA steady state levels of purified B cells activated to switch to IgG3 by LPS in bulk culture. Direct measurement of switching was achieved by enumerating on a percentage basis switched cells in a filter disk culture assay and by FACS analysis. In both bulk culture and the filter disk assay, switching to gamma 3 was equivalent between xid and non-xid B cells.
Biotechnology and Bioengineering | 2003
Kurt Brorson; Sherrie Krejci; Kitty Lee; Elizabeth Hamilton; Kathryn E. Stein; Yuan Xu
Journal of Immunology | 1978
Kathryn E. Stein; Gerald A. Schwarting; Donald M. Marcus
Biotechnology and Bioengineering | 2002
Kurt Brorson; Christina de Wit; Elizabeth Hamilton; Mehnaz Mustafa; Patrick G. Swann; Robert Kiss; Ron Taticek; Gian Polastri; Kathryn E. Stein; Yuan Xu
Biotechnology Progress | 2001
Kurt Brorson; Patrick G. Swann; Elaine F. Lizzio; Tom Maudru; Keith Peden; Kathryn E. Stein
Biologicals | 2002
Kurt Brorson; Yuan Xu; Patrick G. Swann; Elizabeth Hamilton; Mehnaz Mustafa; Christina de Wit; Lenore A. Norling; Kathryn E. Stein