Polyclonal B-cell stimulation by T-cells in a parasitic disease.

Polyclonal B-cell stimulation resulting in B-cell proliferation and antibody production occurs in many infectious diseases. Here, we review our data showing that CD4-positive T-cells are instrumental for such polyclonal B-cell stimulation in a chronic parasitic infection, namely murine cutaneous leishmaniasis. The mechanism used by the T-cells involves a membrane interaction between B-cells and activated T-cells which can take place in the absence of antigen, as well as the action of lymphokines such as IL-4. The membrane interaction does not seem to involve the CD4 molecule on T-cells and MHC class II molecules on B-cells, as it is the case in cognate interaction during antigen-specific stimulation of B-cells by CD4 positive T-helper cells. Whether or not adhesion molecules, e.g. of the integrin family, play a role in the triggering process, is currently under investigation.