Journal of Dental Research, Vol 69, 477-482, Copyright © 1990 by International & American Associations for Dental Research Online Journals
Characterization of monoclonal antibodies against glucosyltransferase synthesizing water-insoluble glucan from Streptococcus sobrinus B13
K. Ochiai, K. Fukushima, T. Shiota and T. Ikeda
Department of Microbiology, Nihon University, School of Dentistry at Matsudo, Chiba, Japan.
Four hybrid cell lines secreting monoclonal antibodies (McAbs) against
glucosyltransferase synthesizing water-insoluble glucan (GTase-I) were
generated by fusion of myeloma cells (P3U1) with splenocytes from mice
immunized with GTase-I from Streptococcus sobrinus B13-N. Cell lines 29E7,
21GC7, and 42HB8 were found to secrete an IgG2a-type immunoglobulin, and
29EG, an IgM-type immunoglobulin. These two isotypes of McAbs were used for
the determination of the binding sites on the GTase molecule, with use of
an enzyme-linked immunosorbent assay. The binding site for McAb 29EG was
different from the site that bound other McAbs. McAb 29EG was found to
inhibit water-insoluble glucan synthesis by GTase-I by 50%, and 29E7 was
found to inhibit it weakly. However, other McAbs did not show any
inhibitory effect in spite of binding to GTase-I. McAb 42HB8 strongly
inhibited GTase-I-mediated adherence of heat-killed cells of S. sobrinus
B-13N to glass surfaces. When the McAbs were tested for their
cross-reactivity among GTase preparations from different mutans
streptococci, McAb 29EG reacted with S. cricetus and S. sobrinus, but not
with other mutans streptococci. Three other McAbs, 21GC7, 29E7, and 42HB8,
were found to react only with the enzyme from S. sobrinus. These findings
indicated that the specificity of the McAbs studied varied with respect to
the antigenic sites on the GTase-I molecule, and that some of the sites
differed in their functions.
