The specificity of T cell help for B cell activation and differentiation is maintained by the brief expression on the T cell surface, following T cell receptor-mediated triggering, of CD40 ligand (CD40L). Interaction of T helper (T h ) cell CD40L with B cell CD40 induces B cell activation, cell surface expression of activation antigens, proliferation, and initiation of immunoglobulin isotype switch. We predicted that in patients with systemic lupus erythematosus (SLE), in whom T h cell-dependent production of autoantibodies results in immune complex-mediated tissue damage, CD40L expression might be augmented, prolonged, or abnormally regulated. Baseline expression of CD40L was increased in some SLE patients studied, when compared with control subjects. While T h cells from normal subjects ( n ϭ 14) and rheumatic disease control patients ( n ϭ 9) showed maximal expression of CD40L, after in vitro activation with phorbol myristate acetate (

BACKGROUNDThe authors performed a comprehensive review of the efficacy of fluorodeoxyglucose positron emission tomography (FDG‐PET) in the detection of primary tumors in patients with cervical metastases from unknown primary tumors.METHODSSixteen studies (involving a total of 302 patients) published between 1994 and 2003 were reviewed. These studies evaluated the role of FDG‐PET in the detection of unknown primary tumors after conventional workup. In all studies, conventional workup included either panendoscopy or computed tomographic/magnetic resonance imaging, and in 10 of 16 studies, both of these diagnostic techniques were performed before diagnosis.RESULTSThe overall sensitivity, specificity, and accuracy rates of FDG‐PET in detecting unknown primary tumors were 88.3%, 74.9%, and 78.8%, respectively. Furthermore, FDG‐PET detected 24.5% of tumors that were not apparent after conventional workup. FDG‐PET imaging also led to the detection of previously unrecognized metastases in 27.1% of patients (regional, 15.9%; distant, 11.2%). FDG‐PET had notably low specificity and a high false‐positive rate (39.3%) in the tonsils. In contrast, the false‐positive rates for FDG‐PET of the base of tongue and hypopharynx were only 21.4% and 8.3%, respectively. FDG‐PET exhibited decreased sensitivity to tumors in the base of tongue (81.5%). The sensitivity of this technique at other sites was 90.5%.CONCLUSIONSFDG‐PET detected primary tumors that went undetected by other modalities in approximately 25% of cases and was sensitive in the detection of previously unrecognized regional or distant metastases in 27% of cases. FDG‐PET had low specificity for tonsillar tumors and low sensitivity for base‐of‐tongue malignancies. Cancer 2004. © 2004 American Cancer Society.

No abstract