CD8 T cell priming by B lymphocytes is CD4 help dependent.
While it is generally accepted that B lymphocytes can present antigen and activate CD4 T cells, priming of CD8 T cells by B lymphocytes remains controversial. Recently, we showed that mice injected with genetically programmed B lymphocytes generate antigen specific CD4 and CD8 T cell responses in vivo that could also be induced in mice lacking functional dendritic cells. To gain further insights into the requirements for T cell priming by antigen-presenting B lymphocytes, in vitro experiments were performed using ovalbumin (OVA) and OVA-specific TCR-transgenic CD4 and CD8 T cells. We found that while B lymphocytes can directly prime CD4 T cells, the activation of CD8 T cells requires T cell help. Transfer experiments show that help can either be contact dependent or be mediated by soluble factors in the supernatants of activated OVA-specific CD4 T cells. Furthermore, the effect of activated CD4 T cells can be replaced by soluble recombinant IL-4. Collectively, the data show the existence of different requirements for priming of CD4 and CD8 T cells and point to the previously unappreciated fact that the induction of CD8 T cell responses by B lymphocytes requires T cell help.
Castiglioni
Paola
P
The Department of Medicine and Cancer Center, University of California in San Diego, La Jolla, USA.
Gerloni
Mara
M
Cortez-Gonzalez
Xochitl
X
Zanetti
Maurizio
M
D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002450:Cell Communication / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D013997:Time Factors
D015847:Interleukin-4