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Infect. Immun., 05 1996, 1672-1678, Vol 64, No. 5
M Levine and FC Miller
Bacterial plaque from the gingival region of teeth contains cytotoxic
agents which lyse undifferentiated human HL60 cells. A small panel of
monoclonal antibodies (MAbs) was found to abrogate much of this activity
and to detect antigens in certain strains of Streptococcus mitis and
Eikenella corrodens. The aim of this study was to determine whether these
bacterial antigens might be involved in HL60 cells cytolysis. Saline
extracts were obtained by homogenizing washed, stationary-phase cells in 65
mM NaCl with a tight-fitting Potter- Elvehjem homogenizer. The extracts of
E. corrodens were toxic to HL60 cells, whereas similar extracts of S. mitis
were nontoxic. Adding plaque toxin-neutralizing MAb 3hE5 blocked the toxic
effect of E. corrodens extract S. mitis extracts contained a single,
strongly reactive antigen of 140 kDa (s140K antigen) detected on Western
blots (immunoblots) by three MAbs from the panel. Rabbit antibodies raised
to this antigen excised from the gel (anti-s140K serum) detected larger
antigens in addition to s140K. E. corrodens extracts contained a number of
antigens detected by the MAbs. Immunoglobulin G (IgG) was purified from
anti-s140K serum by passage through DE52 cellulose. A 100-fold excess (by
weight) of the purified IgG to E. corrodens protein specifically
cross-precipitated an 80-kDa antigen plus a nonantigenic 16-kDa protein,
presumably attached noncovalently. The remaining supernatant fraction had
no toxic activity. A similar ratio of control IgG (from nonimmunized
rabbits) did not precipitate these proteins, and the supernatant fraction
had the same activity as the extract not treated with IgG. The proteins of
80 and 16 kDa were also detected in the anti-s140K immunoprecipitate by
rabbit IgG antibodies to E. corrodens whole cells. The 80-kDa antigen,
alone or complexed with the 16-kDa protein, may be involved in mediating
the toxic activity in E. corrodens and plaque extracts.
Copyright © 1996, American Society for Microbiology
An Eikenella corrodens toxin detected by plaque toxin-neutralizing monoclonal antibodies
Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
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