Antigen-specific activation of B cells in vitro after recruitment of T cell help with superantigen.
BACKGROUND
Human B cells can proliferate in vitro after stimulation with anti-Ig and via the CD40 molecule. Superantigens like SEA which bind to MHC class II antigens on, e.g. B cells can polyclonally activate T cells via interaction with their TcR. The activated T cell subsequently activates the B cells to proliferation and Ig-production.


OBJECTIVE
To investigate whether superantigen could be used to direct polyclonal T cell help to human B cells stimulated by antigen in a restricted manner resulting in production of antigen-specific antibodies in vitro.


METHODS
Purified B cells were preincubated with the antigen in manners allowing crosslinking of surface-Ig. The antigen exposed B cells were then cultured together with autologous CD4+ helper T cells and in the presence of various concentrations of SEA. Antibody production was measured by ELISA after 7-12 days of culture.


RESULTS
Antigen-specific activation of B cells could be obtained after stimulating the B cells with antigen or anti-surface-Ig antibodies in the presence of T helper cells and SEA. The degree of B cell activation (proliferation as well as antibody production) depended on the dose of antigen as well as on the dose of SEA used. Increased crosslinking of surface-Ig on antigen-specific B cells enhanced Ig production. Specific antibody production to a secondary recall antigen (tetanus toxoid) and to primary antigens (DNP and GM2) were obtained. The specific B cell response was dependent on contact between T and B cells.


CONCLUSIONS
the results obtained demonstrate that the superantigen SEA can recruit T cell help to human B cells specifically stimulated by antigens, resulting in production of antigen reactive antibodies in vitro.
Ingvarsson
S
S
Department of Immunotechnology, Lund University, Sweden.
Lagerkvist
A C
AC
Mårtensson
C
C
Granberg
U
U
Ifversen
P
P
Borrebaeck
C A
CA
Carlsson
R
R
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002455:Cell Division; D002478:Cells, Cultured; D004768:Enterotoxins / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D051381:Rats; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D011971:Receptors, Immunologic / Q000276:immunology; D018089:Superantigens / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000888:Antibodies, Anti-Idiotypic; D004768:Enterotoxins; D011947:Receptors, Antigen, B-Cell; D011971:Receptors, Immunologic; D018089:Superantigens; C048844:anti-IgG; C026066:enterotoxin A, Staphylococcal