Model for the role of DSHP in the CTL response to
EBV. (A) EBV-infected B cells secrete hIL-10 and vIL-10.
These cytokines augment proliferation and survival of infected B cells,
up-regulate the inhibitory receptor KIR on CTLs, and act on macrophages
to inhibit T and NK cell function (not shown). During the CTL response
to EBV in normal individuals, DSHP (green) attenuates inhibitory
signals (red) from SHIP, CTLA-4, and/or KIR late in the immune
response. This prolongs the response, allowing rapidly proliferating
EBV-infected cells to be controlled. (B) In XLP patients,
inhibitory signals (red) predominate in the absence of DSHP, and
EBV-infected B cells escape immune surveillance.