Role of Vicia villosa-adherent CD8+ T cells in the immune response to Epstein-Barr virus.

Epstein-Barr virus (EBV) is a lymphotropic human herpesvirus which is also a polyclonal B-cell activator. We show here that Vicia villosa-adherent CD8+ T (VV-T) cells, which have a contrasuppressive activity, play an important role in the B-cell response to EBV and that T-helper cells are not required for antibody production against EBV particles. We have examined this activity by measuring anti-EBV IgM antibody production by B cells in vitro in the presence and the absence of both T-helper and VV-T cells. The presence or absence of T-helper cells did not affect antibody production. Our results suggest that the antigen-presenting activity of VV-T cells was virus specific, while the contrasuppressive activity was not. Control experiments carried out in parallel using human cytomegalovirus (CMV) produced similar results also for CMV-specific IgM production. Taken together, our data lead us to hypothesize that VV-T cells might also play other roles in EBV infections: on the one hand, by presenting EBV to B cells, VV-T cells could contribute to the spread of viral infection of B lymphocytes, as the latter are the exclusive targets for EBV immortalization within the immune system; on the other hand, by inhibiting the effect of T-suppressor cells on T-helper cells, VV-T cells could indirectly help the latter maintain their lymphokine producing activity, especially interleukin-2 and interferon-gamma production, which in turn could directly or indirectly (i.e., by stimulating natural killer and T cells) contribute to control of the EBV infection.