In vitro immunization with antigen directly blotted from SDS-polyacrylamide gels to polyvinylidene difluoride membranes

Successful in vitro antigen-dependent activation of 24-hour-old peripheral blood lymphocytes

We describe a simple, rapid and reproducible in vitro culture system in which human peripheral blood lymphocytes (PBLs), donated 24 h prior to initiation of culture can be stimulated to produce antigen-specific antibodies. Peripheral blood lymphocytes purified by Ficoll-Hypaque centrifugation were passed over a G10 Sephadex column and then activated in vitro in the presence of 0.003% staphylococcus Cowan A, 2.8 x 10(-6) M indomethacin and appropriate concentrations of tetanus toxoid antigen. After the first 24 h in culture, a five-fold concentrated supernatant from an allogeneic mixed lymphocyte culture was added. The cell surface phenotypes of the PBLs were analyzed by flow cytometry at the initiation and termination of culture, in order to provide a comprehensive characterization of the cellular composition of a successful in vitro stimulation system. Our results clearly show that the majority of peripheral blood B cells can be induced to an activated stage (blast transformation) and interleukin 2 (IL-2) receptor expression, following very simple manipulations of the lymphoid population. Tetanus toxoid-specific antibody production can be readily generated in this cell population. In contrast, T cells were not activated to express IL-2 receptors and reach blast transformation, and did not show appreciable proliferation. Our system provides a population of B cells producing antibodies of desired specificity which could be utilized for the generation of human hybridomas or could serve as a donor population for antibody engineering via the combinatorial library approach. Careful light scattering and cell surface phenotypic analyses of the cells entering, proliferating and differentiating in these cultures enabled several novel observations to be made.

In vitro immunization: generation of neutralizing monoclonal antibodies to human interleukin-10

The potential of the in vitro immunization technique to evoke an immune response against an immunomodulatory protein was evaluated using, as antigen, human interleukin-10 (IL-10), a novel cytokine with pleiotropic effects on human and murine lymphocytes and macrophages. After pre-priming the support cells for 48 h and subsequent 3-day stimulation of splenocytes from a non-immune BALB/c mouse with recombinant human IL-10 (rhIL-10; 2 micrograms/ml), significant stimulation of splenocytes was observed. 7 days after fusion with the non-secreting myeloma line X63/Ag8.653, IL-10-specific antibodies were detected by ELISA and dot blot in more than 70% of the hybridoma supernatants. After limiting dilution of the hybridoma cells showing IL-10-neutralizing activity in a bioassay using murine MC/9 mast cells, the isotype of the monoclonal antibodies (mAbs) obtained was 20% IgM, 16% IgG and 6% IgA. All other antibodies elicited IgM as well as IgG isotypes. The neutralizing activity of the specific mAbs tested was dose-dependent. Our results show that in vitro immunization can be employed successfully to generate functional mAbs to immunomodulatory proteins, even if these exhibit cross-species activity.