Antigen presentation is enhanced by targeting antigen to the Fc epsilon RII by antigen-anti-Fc epsilon RII conjugates.
Targeting Ag to the Fc epsilon RII by Ag-specific IgE has been shown to be an efficient means of enhancing Ag presentation by B cells to Ag-specific T cells. To take advantage of the Fc epsilon RII as a targeting molecule and to investigate whether IgE was required for mediation of the enhanced stimulation, Ag was covalently coupled to anti-Fc epsilon RII by using heterobifunctional crosslinking reagents. These Ag-Ab conjugates were used with T cell lines specific for the Ags, OVA (BB6.5) or rabbit gamma-globulin (CDC35 and D1.6), and splenic B cells to examine both B cell and T cell proliferation in vitro. Significant presentation of Ag-anti-Fc epsilon RII conjugates was apparent at doses of Ag 1,000- to 10,000-fold lower than seen with unconjugated Ag alone. Ag presentation with the use of anti-Fc epsilon RII-Ag conjugates was as good as or better than conjugates with Ab to the adhesion molecule Pgp-1 or control Ab in T cell proliferation and better than those conjugates in B cell proliferation assays (10- to 100-fold). Anti-Fc epsilon RII-Ag conjugates were clearly more effectively presented than Ag-anti-Fc gamma RII conjugates (> 100-fold). Mouse Fc epsilon RII is presently known to be expressed on B cells and follicular dendritic cells and these in vitro results suggest that the conjugates would be useful tools for investigating the role of IgE-mediated B cell Ag presentation in vivo. BALB/c mice immunized with OVA-anti-Fc epsilon RII conjugates made a quite significant OVA-specific IgG1 response and a detectable IgE response. No detectable Ab was produced in response to OVA alone and a minimal response was seen when an isotype-matched control conjugate was used. Thus, the results indicate that Fc epsilon RII targeting is operative both in vivo and in vitro.
Squire
C M
CM
Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond 23298.
Studer
E J
EJ
Lees
A
A
Finkelman
F D
FD
Conrad
D H
DH
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D017951:Antigen Presentation; D001402:B-Lymphocytes / Q000276:immunology; D002460:Cell Line; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000276:immunology; D011817:Rabbits; D051381:Rats; D017455:Receptors, IgE / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D005719:gamma-Globulins / Q000276:immunology
D000911:Antibodies, Monoclonal; D017455:Receptors, IgE; D005719:gamma-Globulins; D007073:Immunoglobulin E; D010047:Ovalbumin