Wild-type CD4+ T cells (black circles), but not SAP-deficient CD4+ T cells (closed squares), restore antibody production in SAP-deficient mice.

CD4+ T cells that lack the adaptor protein SAP are little help to B cells, according to Cannons and colleagues on page 1551. But their unhelpful nature does not result from a failure to produce T helper (Th)-2 cytokines, as the authors had previously thought.

The absence of SAP wreaks havoc on the immune system. SAP—the adaptor that links the SLAM family of activating receptors to the downstream signaling protein Fyn—is expressed in most immune cell types and its absence causes a bevy of immune defects.

Mutations in SAP cause a rare disease called X-linked lymphoproliferative disease (XLP), which is characterized in part by extreme susceptibility to Epstein Barr virus (EBV) infection. Those who survive EBV infection often have long-term antibody...

The Rockefeller University Press
2006
The Rockefeller University Press
2006
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