2B4-mediated activation of human natural killer cells

2B4 is a member of the CD2 subset of the immunoglobulin superfamily of cell surface receptors. Other members of this family include CD2, CD48, CD58, CD84, signaling lymphocytic activation molecule and Ly-9. Some of these molecules are activating structures expressed by natural killer cells and T cells. We have recently cloned and characterised the human homologue of 2B4 and found that the cytoplasmic domain of 2B4 can interact with SAP, a signaling adaptor protein that is mutated in the immunodeficiency X-linked lymphoproliferative disease (XLP). Additionally, the natural ligand of 2B4 has been identified as CD48. These findings have facilitated the investigation of the functional role of this receptor-ligand pair, and associated signal transduction pathways, on immune cells. In this study, it was found that the interaction between 2B4 on effector cells and CD48 on target cells induced NK-cell activation, as evidenced by increased cytotoxicity and secretion of IFN-gamma. The responses induced by ligation of 2B4 could be reduced by the co-ligation of inhibitory receptors expressed by NK cells, demonstrating that activation signals delivered via 2B4 can be regulated by the action of certain inhibitory receptors. Because the signalling pathway of 2B4 involves SAP, it is possible that 2B4-mediated NK-cell activation may be compromised in patients with XLP due to mutations in SAP. This may contribute to the phenotype and progression of this disease.     

NKG2D ligands: unconventional MHC class I-like molecules exploited by viruses and cancer

Our best teachers in revealing the importance of immune pathways are viruses and cancers that have subverted the most prominent pathways to escape from immune recognition. Viruses and cancer impair antigen presentation by classical MHC class I to escape adaptive immunity. The activating receptor NKG2D and its MHC class I-like ligands are other recently defined innate and adaptive immune pathways exploited by viruses and cancer. This review discusses recent advances in the understanding of how NKG2D, expressed on innate immune cells including natural killer cells, gammadelta+ T cells and macrophages, and adaptive immune cells such as CD8+ T cells, recognize stress-induced, MHC class I-like, self-ligands. Moreover, we describe how viruses and cancer have developed strategies to evade this recognition pathway.     

Innovative approaches in governance: a case study of the Greater Southeast Healthcare System

Washington, D.C.'s Greater Southeast Healthcare System is like a spinning top--balanced by internal energy and driven by external forces. Those forces, the voices of the system's community, have provided Greater Southeast with direction and governance that have brought the system national recognition as well as an agenda for change. Even more important, they have resulted in services that have grown deep roots in the community.     

Peptide vaccination using nonionic block copolymers induces protective anti-viral CTL responses.

High molecular weight nonionic block copolymers have been developed as vaccine adjuvants. We employed these adjuvants in water-in-oil emulsion and multiple emulsion formulations with a synthetic peptide-based antigen vaccine to test their ability to prime anti-viral CD8(+) T cell responses. Vaccines were made using the H-2(d)-restricted immunodominant peptide from lymphocytic choriomeningitis virus (LCMV), NP118-126, and administered to BALB/c ByJ (H-2(d)) mice. Peptide-containing emulsions were able to induce NP118-126 specific CTL and IFN-gamma secreting CD8(+) T cells in the vaccinated mice and these responses were maintained for at least 90 days post immunization. At all times, the responses induced by the copolymer formulations were equal to, or better than, formulations based on incomplete Freund's adjuvant (IFA). In addition, the responses induced by prophylactic vaccination using the multiple emulsion formulation resulted in accelerated viral clearance following infection with a strain of LCMV (clone 13) that causes a persistent infection in na?ve adult mice. These results indicate that peptide vaccination using a formulation based on high molecular weight nonionic block copolymer in a simple water-in-oil or a multiple emulsion format can induce virus-specific CD8(+) T cell responses and confer protection sufficient enough to prevent the establishment of a persistent infection.     

Combination of fludarabine and mitoxantrone in untreated stages III and IV low-grade lymphoma: S9501.

PURPOSE: To determine the efficacy of combination fludarabine and mitoxantrone (FN) in untreated stages III and IV low-grade lymphoma. The major end point was to estimate progression-free survival (PFS) in all eligible patients. PATIENTS AND METHODS: Seventy-eight eligible patients were registered. Chemotherapy courses were administered every 4 weeks with mitoxantrone 10 mg/m2 on day 1 and fludarabine 25 mg/m2 on days 1, 2, and 3 for a total of six to eight cycles. Pneumocystis carinii prophylaxis was required. RESULTS: Seventy-three patients (94%) attained an objective response. Complete remission was demonstrated in 34 patients (44%) and partial remission was demonstrated in 39 patients (50%). With a median follow-up time of 5.5 years, the median PFS was 32 months, with a 4-year PFS rate of 38%. Median survival has not been reached and 88% of all patients are alive at 4 years. The application of the International Prognostic Index and serologic staging showed significant differences in PFS in all risk groups, whereas overall survival was markedly worse for the highest-risk group in either prognostic model. Three prior Southwest Oncology Group trials using a regimen of cyclophosphamide, doxorubicin, vincristine, and prednisone or a combination of prednisone, vincristine, methotrexate, cytarabine, cyclophosphamide, etoposide, nitrogen mustard, vincristine, procarbazine, and prednisone in similar patient populations demonstrated comparable clinical outcome, although the 4-year survival for FN was better. FN was well tolerated, but mild to severe reversible myelosuppression was noted. Other complications were rare. CONCLUSION: FN is an effective, safe chemotherapy combination for patients with advanced-stage, low-grade lymphoma. Clinical outcomes were comparable to prior published data using anthracycline-based regimens.     

Differences in cancer incidence among Indians in Alaska and New Mexico and U.S. Whites, 1993-2002.

Cancer incidence for American Indians and Alaska Natives is typically reported as a single rate for all U.S. indigenous populations combined. Previously reported combined rates suggest that American Indians and Alaska Natives have lower cancer incidence rates compared with the U.S. population. Alaska Native people comprise three major ethnic groups: Eskimo, Indian, and Aleut people. We examined cancer incidence from only Alaska Indians and compared incidence rates with an American Indian population living in New Mexico. These data indicate striking differences in cancer patterns between two American Indian populations. Cancer data for the years 1993 to 2002 for American Indians of New Mexico and U.S. Whites are from the National Cancer Institute Surveillance, Epidemiology, and End Results Program Public-use data set. Data for Alaska Indians are from the Alaska Native Tumor Registry, which is also a Surveillance Epidemiology and End Results Program participant. Overall, cancer incidence rates for all sites combined in New Mexico Indian men and women were lower than U.S. White rates, whereas Alaska Indian men and women exceeded U.S. rates. In comparing Alaska and New Mexico Indians, we observed a 2.5-fold higher incidence of cancer among Alaska Indians. The largest differences between the two Indian populations were noted primarily in cancers associated with tobacco use, including cancers of the oral cavity/pharynx, esophagus (only in men), colon and rectum, pancreas, larynx (men), lung, prostate, and urinary bladder (men). Lung cancer rates in Alaska Indian men and women were 7 and 10 times those of New Mexico Indian men and women.