High-functional-avidity cytotoxic T lymphocyte responses to HLA-B-restricted Gag-derived epitopes associated with relative HIV control.

Virus-specific cytotoxic T lymphocytes (CTL) with high levels of functional avidity have been associated with viral clearance in hepatitis C virus infection and with enhanced antiviral protective immunity in animal models. However, the role of functional avidity as a determinant of HIV-specific CTL efficacy remains to be assessed. Here we measured the functional avidities of HIV-specific CTL responses targeting 20 different, optimally defined CTL epitopes restricted by 13 different HLA class I alleles in a cohort comprising 44 HIV controllers and 68 HIV noncontrollers. Responses restricted by HLA-B alleles and responses targeting epitopes located in HIV Gag exhibited significantly higher functional avidities than responses restricted by HLA-A or HLA-C molecules (P = 0.0003) or responses targeting epitopes outside Gag (P < 0.0001). The functional avidities of Gag-specific and HLA-B-restricted responses were higher in HIV controllers than in noncontrollers (P = 0.014 and P = 0.018) and were not restored in HIV noncontrollers initiating antiretroviral therapy. T-cell receptor (TCR) analyses revealed narrower TCR repertoires in higher-avidity CTL populations, which were dominated by public TCR sequences in HIV controllers. Together, these data link the presence of high-avidity Gag-specific and HLA-B-restricted CTL responses with viral suppression in vivo and provide new insights into the immune parameters that mediate spontaneous control of HIV infection.

Viral adaptation to immune selection pressure by HLA class I-restricted CTL responses targeting epitopes in HIV frameshift sequences.

CD8+ cytotoxic T lymphocyte (CTL)-mediated immune responses to HIV contribute to viral control in vivo. Epitopes encoded by alternative reading frame (ARF) peptides may be targeted by CTLs as well, but their frequency and in vivo relevance are unknown. Using host genetic (human leukocyte antigen [HLA]) and plasma viral sequence information from 765 HIV-infected subjects, we identified 64 statistically significant (q<0.2) associations between specific HLA alleles and sequence polymorphisms in alternate reading frames of gag, pol, and nef that did not affect the regular frame protein sequence. Peptides spanning the top 20 HLA-associated imprints were used to test for ex vivo immune responses in 85 HIV-infected subjects and showed responses to 10 of these ARF peptides. The most frequent response recognized an HLA-A*03-restricted +2 frame-encoded epitope containing a unique A*03-associated polymorphism at position 6. Epitope-specific CTLs efficiently inhibited viral replication in vitro when viruses containing the wild-type sequence but not the observed polymorphism were tested. Mutating alternative internal start codons abrogated the CTL-mediated inhibition of viral replication. These data indicate that responses to ARF-encoded HIV epitopes are induced during natural infection, can contribute to viral control in vivo, and drive viral evolution on a population level.

Structural basis for recognition of SMRT/N-CoR by the MYND domain and its contribution to AML1/ETO's activity.

AML1/ETO results from the t(8;21) associated with 12%-15% of acute myeloid leukemia. The AML1/ETO MYND domain mediates interactions with the corepressors SMRT and N-CoR and contributes to AML1/ETO's ability to repress proliferation and differentiation of primary bone marrow cells as well as to enhance their self renewal in vitro. We solved the solution structure of the MYND domain and show it to be structurally homologous to the PHD and RING finger families of proteins. We also determined the solution structure of an MYND-SMRT peptide complex. We demonstrated that a single amino acid substitution that disrupts the interaction between the MYND domain and the SMRT peptide attenuated AML1/ETO's effects on proliferation, differentiation, and gene expression.

Breast cancer in the very elderly: treatment patterns and complications in a tertiary cancer center.

BACKGROUND: The risk of developing breast cancer rises with increasing age. The very elderly population (80 years of age and greater) is often excluded from both clinical trials and retrospective analyses. We performed a retrospective review of the very elderly population treated at our institution in order to assess treatment patterns and the safety of therapy in an older population. DATA SOURCES: In this institutional experience at a comprehensive cancer center, we retrospectively reviewed the charts of patients 80 years and older diagnosed with a new breast cancer between September 1, 1989, and September 1, 2004. RESULTS: Two hundred thirteen patients were identified for this study. Median age was 83 (range 80-97). Median survival was 7.28 years, with a median follow up of 4 years for patients still alive at the end of the study period. Ninety-eight percent of patients (208/213) received 1 or more components of recommended multimodality treatment. Five patients refused all treatment. Overall, complications affected 12% of patients who received treatment (26/208). There were 2 deaths, 1 after surgery and 1 related to chemotherapy. The majority, 69% (18/26), of the documented complications were classified as minor. Surgery resulted in complications in 6% (11/188) of patients. Five percent (5/112) of patients who received radiation suffered adverse effects. Chemotherapy-related complications affected 30% (6/18) of treated patients. Hormonal agents resulted in complications in 3% (3/112) of patients. No correlation between the American Society of Anesthesiologists score and incidence of complication was observed (P = .58). CONCLUSIONS: Very elderly patients can be safely treated with surgery and radiation in accordance with accepted recommendations for their stage of breast cancer. Treatment with surgery and/or radiation should be considered despite age and moderate comorbidity in order to affect locoregional control. Chemotherapy results in a significant incidence of complications and should be cautiously implemented in this age group. A prospective trial is necessary to assess the necessity of aggressive multimodality therapy in this very elderly population.

Sedimentation velocity studies of the high-molecular weight aggregates of the HIV gp41 ectodomain.

Accumulation of the HIV envelope protein gp41 is observed in the brain tissues of patients suffering from HIV-associated dementia. Previously, we have shown by electron microscopy that the extracellular domain of SIV gp41, which is analogous to that of HIV, forms high-molecular weight aggregates in vitro, and we have postulated that such high-molecular weight aggregates are responsible for neurological damage in a manner similar to protein deposition diseases such as Alzheimer's and the prion diseases. In this manuscript, we have characterized the self-association of the HIV gp41 ectodomain by sedimentation velocity. We show that discreet species of the gp41 high-molecular weight aggregates are present. The maximum population occurs at 20 S, which corresponds to ~5 trimers of gp41, suggesting that five trimers are required for nucleation of the high-molecular weight aggregates. The concentration dependence of the gp41 self-association indicates that it occurs by mass action. The temperature dependence of gp41 self-association suggests that it is driven by entropy, indicating that intermolecular hydrophobic interactions between trimers of gp41 are driving the association.

Altered affinity of CBF beta-SMMHC for Runx1 explains its role in leukemogenesis.

Chromosomal translocations involving the human CBFB gene, which codes for the non-DNA binding subunit of CBF (CBF beta), are associated with a large percentage of human leukemias. The translocation inv(16) that disrupts the CBFB gene produces a chimeric protein composed of the heterodimerization domain of CBF beta fused to the C-terminal coiled-coil domain from smooth muscle myosin heavy chain (CBF beta-SMMHC). Isothermal titration calorimetry results show that this fusion protein binds the Runt domain from Runx1 (CBF alpha) with higher affinity than the native CBF beta protein. NMR studies identify interactions in the CBF beta portion of the molecule, as well as the SMMHC coiled-coil domain. This higher affinity provides an explanation for the dominant negative phenotype associated with a knock-in of the CBFB-MYH11 gene and also helps to provide a rationale for the leukemia-associated dysregulation of hematopoietic development that this protein causes.