The conjugative transfer region 1 (Tra1) of the IncHI1 plasmid R27 was subjected to DNA sequence analysis, mutagenesis, genetic complementation, and an H-pilus-specific phage assay. Analysis of the nucleotide sequence indicated that the Tra1 region contains genes coding for mating pair formation (

Killer cell Ig-like receptors (KIRs) are MHC class I-specific receptors expressed in NK and T lymphocytes. KIR antagonism of activation signals occurs at the immune synapse between the effector and target cells. The processes that regulate clustering of KIR are not well defined. We have expressed KIR-GFP receptor chimeras in two human NK-like lines, YTS and NK92. In this study, we show that the frequency of KIR enrichment at the synapse was decreased for a KIR that lacks a portion of the cytoplasmic tail. Strikingly, blocking actin polymerization with a high dose of cytochalasin D also substantially decreased clustering of KIR as well as KIR-induced clustering of HLA-C-GFP in target cells. However, the effect of inhibiting actin polymerization was only clearly evident at the earlier time points after cell mixing, and eventually clustering of KIR and HLA-C occurred independently of actin remodeling. Although treatment with anti-LFA-1 also decreased conjugate formation, the frequency of KIR clustering remained normal within the population of conjugates that did form, suggesting that the effect of cytochalasin D is not solely through LFA-1. Collectively, these data suggest that the actin cytoskeleton and the cytoplasmic tail of KIR regulate the efficiency by which KIR accumulates at inhibitory NK cell synapses.

Target cell lysis by natural killer cells is inhibited by killer cell immunoglobulin-like receptors (KIR) that bind major histocompatibility complex class I molecules. Many lymphocyte receptors, including KIR, become enriched at the interface with ligand-bearing cells. The contribution of the enrichment to inhibitory signaling has not been determined. We now describe a KIR variant with enhanced green fluorescent protein (EGFP) at the N terminus that can mediate inhibitory signaling, but its enrichment is markedly reduced. This receptor is only slightly weaker at inhibiting lysis than the same KIR tagged with EGFP in the cytoplasmic tail, even though the latter enriched as extensively as wild-type KIR. A slight defect was also detected in the ability of the receptor to reduce adhesion to target cells and for binding of a soluble counterpart to cell surface HLA-C. Our findings suggest that the strength of the interaction required to readily detect receptor enrichment exceeds that required for signaling.

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552 Background: Cancer staging systems convey valuable prognostic information to both clinicians and patients. Currently, colon cancer is staged according to the American Joint Committee on Cancer (AJCC) TNM classification system. However, survival estimates for patients with the same stage of colon cancer may vary considerably due to other factors including age, sex, grade, and number of lymph nodes sampled. The objectives of this study are to 1) assess the accuracy of the seventh edition of the TNM classification system in predicting survival of patients with primary colon cancer after curative-intent surgery, and 2) evaluate the utility of incorporating additional demographic and tumor variables beyond TNM staging in improving prognostic accuracy. Methods: Patients with curative-intent resection of a first primary adenocarcinoma of the colon at the time of referral to the Cross Cancer Institute between 2004 and 2007 were identified from the Alberta Cancer Registry. We constructed three multivariate Cox’s proportional hazard models to explore the effect of supplementing TNM staging with additional demographic and tumor variables in predicting overall survival (OS). Results: 559 consecutive patients with complete chart records were identified. 52 % (n=290) were male; median age was 74. In the first model based only on T and N elements, N2 disease was correlated with increased mortality (hazard ratio [HR], 2.546; p<0.0001). When the number of lymph nodes examined (HR, 0.980; p=0.034) and number of metastatic lymph nodes detected (HR, 1.094; p<0.0001) were substituted for the N-staging element, both variables correlated positively and negatively with outcome, respectively. Finally, when tumor grade, sex and age were incorporated into the model, number of examined lymph nodes (HR, 0.980; p=0.029) and those containing tumor (HR, 1.093; p<0.0001) remained independent predictors of OS. Conclusions: Incorporating readily available demographic and tumor variables, such as age, sex and number of lymph nodes examined, can enhance the current TNM staging system and improve prognostication in early stage colon cancer.