Adjuvant actions of polyclonal lymphocyte activators. V. Proliferation of macrophage colony-forming cells in the draining lymph node

GD3/proteosome vaccines induce consistent IgM antibodies against the ganglioside GD3

The gangliosides of melanoma and other tumours of neuroectodermal origin are suitable targets for immune intervention with tumour vaccines. The optimal vaccines in current use contain ganglioside plus bacillus Calmette-Guérin and induce considerable morbidity. We have screened a variety of new adjuvants in the mouse, and describe one antigen-delivery system, proteosomes, which is especially effective. Highly hydrophobic Neisserial outer membrane proteins (OMP) form multimolecular liposome-like vesicular structures termed proteosomes which can readily incorporate amphiphilic molecules such as GD3 ganglioside. The optimal GD3/proteosome vaccine formulation for induction of GD3 antibodies in the mouse is determined. Interestingly, the use of potent immunological adjuvants in addition to proteosomes augments the IgM and IgG antibody titres against OMP in these vaccines but GD3 antibody titres are unaffected. The application of proteosomes to enhance the immune response to GD3 extends the concept of the proteosome immunopotentiating system from lipopeptides to amphipathic carbohydrate epitopes such as cell-surface gangliosides. The demonstrated safety of meningococcal OMP in humans and the data in mice presented here suggest that proteosome vaccines have potential for augmenting the immunogenicity of amphipathic tumour antigens in humans.

Regulation of isotype immunoglobulin production by adjuvants in vivo

Mice were immunized against fluorescein isothiocyanate (FITC)-labelled human gamma globulin (HGG) or dextran sulphate (DXS) in the absence or presence of different adjuvants. The immune response was assayed as the total Ig-secreting cells and FITC-specific plaque-forming cells (PFC) found in various lymphoid organs. The adjuvants influenced the isotype of antibodies produced to the same antigenic determinant. The PFC of different IgG subclasses were favoured by different adjuvants. The IgG3 isotype was produced mainly after immunization with either antigen and lipopolysaccharide (LPS) or Li salt as adjuvant; IgG1 was produced with incomplete Freund's adjuvant (IFA), complete Freund's adjuvant (CFA), alum, poly I:C, Quil A, Be salt, and poly A:U. Some of the above adjuvants (Be salt and poly A:U) favoured the production of IgG2b, and others (CFA, alum, Quil A, and poly I:C) favoured the IgG2a isotype besides the main isotype. Attempts were made to correlate the activation by the various adjuvants of certain TH subtypes with the isotypes produced.

Differential response of B cells in the lymph node and the spleen to bacterial lipopolysaccharide

In vivo polyclonal activation of B cells in the lymph nodes and the spleens of mice injected with bacterial lipopolysaccharide (LPS) was compared. The peak of anti-trinitrophenylated sheep red blood cells plaque-forming cell (PFC) response in the lymph node was reached 6-8 days after the injection of LPS while that in the spleen was reached at 2 days. The maximal increase in the total number of Ig-producing cells in the lymph node also occurred at the later stage. These differences in time courses of polyclonal activation of B cells between the lymph node and the spleen were not due to the absence of B cells in the lymph node, migration of PFC from the spleen to the lymph node, or qualitative differences of B cells. This phenomenon was dependent on the environmental difference between the lymph node and the spleen, because B cells from the lymph node could respond to LPS rapidly in the spleen. Further, the polyclonal activation of B cells was accelerated in the lymph nodes of mice receiving prior injection of LPS. In in vitro cultures of lymph node cells of those mice, a significant amount of interleukin-1 could be detected by stimulation of LPS. It was possible that the delayed activation of B cells in the lymph node was due to the time lag necessary for construction of the environmental condition suitable for activation of B cells, whereas in the spleen this condition can be provided without delay.