Research article

Human CD81 directly enhances T_h1 and T_h2 cell activation, but preferentially induces proliferation of T_h2 cells upon long-term stimulation

Holden T Maecker

BD Biosciences, Immunocytometry Systems, 2350 Qume Drive, San Jose, CA 95131, USA

author email corresponding author email

BMC Immunology 2003, 4:1doi:10.1186/1471-2172-4-1

Published:	19 February 2003

Abstract

Background

CD81, a cell-surface protein of the tetraspanin superfamily, has been shown to costimulate T cell activation in murine T cells, and is involved in development of Th2 immune responses in mice.

Results

Here it is shown that stimulation of CD81 on human T cells can enhance T cell activation by antigen or superantigen, causing an increase in the early activation marker CD69, and increasing the number of cytokine-producing and proliferating T cells. Interestingly, CD81 costimulates cytokine production by T cells producing both Th1 and Th2 cytokines. Although human CD81 is highly expressed on non-T as well as T cells, CD81 costimulation appears to act directly on T cells. Pre-incubation of purified T cells with anti-CD81 antibody is sufficient to increase T cell activation, while pre-incubation of non-T cells is not. However, long-term polyclonal stimulation of T cells by anti-CD3 antibody, in the presence of CD81 costimulation, biases T cells towards the production of IL-4 and not IFNγ. This is accomplished by a preferential proliferation of IL-4-producing cells.

Conclusion

Thus, signalling through CD81 on T cells costimulates both Th1 and Th2 cells, but increases the number of Th2 cells during long-term activation.