T cell activity and cytokine production in X-linked agammaglobulinemia: implications for vaccination strategies.

In the 5 X-linked agammaglobulinemia (XLA) patients studied we show that memory T cells are present and that T lymphocytes proliferate normally to mitogens, monoclonal antibodies and, in particular, to recall antigens demonstrating normal in vivo T cell priming despite the absence of B cells. Furthermore, in vitro T cell activation in response to both T cell receptor-independent and T-cell receptor-dependent signals leads to a pattern of cytokine production characteristic of primed T cells and necessary for normal T cell function. These data are in good agreement with results obtained in gene-targeted mice and further support the concept that the absence of B cells does not impair induction of in vivo T cell memory and effector function which is generally considered to be of great importance in conferring protection against viral infections. Thus, while there is no risk of inducing infections in XLA patients by administering vaccines containing killed viruses or recombinant viral proteins, stimulation of T cell immunity by such vaccines may be of potential benefit particularly in the defense against infections with viruses such as the hepatitis B virus to which hypogammaglobulinemic patients are particularly exposed.