title: Generation and characterization of high affinity human monoclonal antibodies that neutralize staphylococcal enterotoxin B.
abstract: BACKGROUND
  Staphylococcal enterotoxins are considered potential biowarfare agents that can be spread through ingestion or inhalation. Staphylococcal enterotoxin B (SEB) is a widely studied superantigen that can directly stimulate T-cells to release a massive amount of proinflammatory cytokines by bridging the MHC II molecules on an antigen presenting cell (APC) and the Vβ chains of the T-cell receptor (TCR). This potentially can lead to toxic, debilitating and lethal effects. Currently, there are no preventative measures for SEB exposure, only supportive therapies.
  
  
  METHODS
  To develop a potential therapeutic candidate to combat SEB exposure, we have generated three human B-cell hybridomas that produce human monoclonal antibodies (HuMAbs) to SEB. These HuMAbs were screened for specificity, affinity and the ability to block SEB activity in vitro as well as its lethal effect in vivo.
  
  
  RESULTS
  The high-affinity HuMAbs, as determined by BiaCore analysis, were specific to SEB with minimal crossreactivity to related toxins by ELISA. In an immunoblotting experiment, our HuMAbs bound SEB mixed in a cell lysate and did not bind any of the lysate proteins. In an in vitro cell-based assay, these HuMAbs could inhibit SEB-induced secretion of the proinflammatory cytokines (INF-γ and TNF-α) by primary human lymphocytes with high potency. In an in vivo LPS-potentiated mouse model, our lead antibody, HuMAb-154, was capable of neutralizing up to 100 μg of SEB challenge equivalent to 500 times over the reported LD50 (0.2 μg) , protecting mice from death. Extended survival was also observed when HuMAb-154 was administered after SEB challenge.
  
  
  CONCLUSIONS
  We have generated high-affinity SEB-specific antibodies capable of neutralizing SEB in vitro as well as in vivo in a mouse model. Taken together, these results suggest that our antibodies hold the potential as passive immunotherapies for both prophylactic and therapeutic countermeasures of SEB exposure.
authors.affiliation: Morphotek Inc,, 210 Welsh Pool Road, Exton, PA, USA. grasso@morphotek.com.
authors.forename: Brian
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authors.lastname: Drozdowski
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Brad
authors.initials: B
authors.lastname: Kline
authors.forename: Jared
authors.initials: J
authors.lastname: Spidel
authors.forename: Yin Yin
authors.initials: YY
authors.lastname: Chan
authors.forename: Earl
authors.initials: E
authors.lastname: Albone
authors.forename: Howard
authors.initials: H
authors.lastname: Turchin
authors.forename: Qimin
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authors.lastname: Chao
authors.forename: Marianne
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authors.lastname: Henry
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Balogach
authors.forename: Eric
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authors.lastname: Routhier
authors.forename: Sina
authors.initials: S
authors.lastname: Bavari
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Nicolaides
authors.forename: Philip M
authors.initials: PM
authors.lastname: Sass
authors.forename: Luigi
authors.initials: L
authors.lastname: Grasso