Compromised OX40 function in CD28-deficient mice is linked with failure to develop CXC chemokine receptor 5-positive CD4 cells and germinal centers

Mice rendered deficient in CD28 signaling by the soluble competitor, cytotoxic T lymphocyte-associated molecule 4-immunoglobulin G1 fusion protein (CTLA4-Ig), fail to upregulate OX40 expression in vivo or form germinal centers after immunization. This is associated with impaired interleukin 4 production and a lack of CXC chemokine receptor (CXCR)5 on CD4 T cells, a chemokine receptor linked with migration into B follicles. Germinal center formation is restored in CTLA4-Ig transgenic mice by coinjection of an agonistic monoclonal antibody to CD28, but this is substantially inhibited if OX40 interactions are interrupted by simultaneous injection of an OX40-Ig fusion protein. These data suggest that CD28-dependent OX40 ligation of CD4 T cells at the time of priming is linked with upregulation of CXCR5 expression, and migration of T cells into B cell areas to support germinal center formation

Properties of monoclonal antibodies to human immunoglobulin kappa and lambda chains.

Hybridomas have been produced from mice immunized with human IgG. Culture supernates were assayed for the presence of antibody-producing cells by passive haemagglutination. Hybridomas producing antibodies to human kappa (kappa) and lambda (lambda) light chains have been cloned and grown as ascitic tumours in BALB/c mice. The antigen-binding characteristics of the monoclonal antibodies, contained in the ascitic fluid, were assessed by haemagglutination inhibition, ELISA and radioimmunoassay systems and by the binding of radiolabelled antigen in analytical flat-bed iso-electric focussing gels. One monoclonal anti-kappa reacted better with free than with combined kappa chains; for another the reverse was true. Antibody fractions separated by DEAE chromatography of ascitic fluids were coupled to ox red cells with chromic chloride and compared with polyclonal antibodies for the detection of cell-surface immunoglobulins