TCR affinity associated with functional differences between dominant and subdominant SIV epitope-specific CD8+ T cells in Mamu-A*01+ rhesus monkeys

Many of the factors that contribute to CD8+ T cell immunodominance hierarchies during viral infection are known. However, the functional differences that exist between dominant and subdominant epitope-specific CD8+ T cells remain poorly understood. In this study, we characterized the phenotypic and functional differences between dominant and subdominant simian immunodeficiency virus (SIV) epitope-specific CD8+ T cells restricted by the major histocompatibility complex (MHC) class I allele Mamu-A*01 during acute and chronic SIV infection. Whole genome expression analyses during acute infection revealed that dominant SIV epitope-specific CD8+ T cells had a gene expression profile consistent with greater maturity and higher cytotoxic potential than subdominant epitope-specific CD8+ T cells. Flow-cytometric measurements of protein expression and anti-viral functionality during chronic infection confirmed these phenotypic and functional differences. Expression analyses of exhaustion-associated genes indicated that LAG-3 and CTLA-4 were more highly expressed in the dominant epitope-specific cells during acute SIV infection. Interestingly, only LAG-3 expression remained high during chronic infection in dominant epitope-specific cells. We also explored the binding interaction between peptide:MHC (pMHC) complexes and their cognate TCRs to determine their role in the establishment of immunodominance hierarchies. We found that epitope dominance was associated with higher TCR:pMHC affinity. These studies demonstrate that significant functional differences exist between dominant and subdominant epitope-specific CD8+ T cells within MHC-restricted immunodominance hierarchies and suggest that TCR:pMHC affinity may play an important role in determining the frequency and functionality of these cell populations. These findings advance our understanding of the regulation of T cell immunodominance and will aid HIV vaccine design.

Burden of upper respiratory illnesses among college and university students: 2002–2003 and 2003–2004 cohorts

Upper respiratory illnesses, including colds and influenza-like illnesses, are common among college and university students. We have established an ongoing, serial cohort study to assess the occurrences of these illnesses among college and university students as well as the impact of these illnesses on overall health, school and work performance, and health care use. In this paper we report on the first 2 years of this study (2002-2003 and 2003-2004). For each year, more than 4000 students responded to the e-mail invitations to participate, and they provided more than 3000 person-seasons of follow-up information during the monthly surveys conducted November-April. In both years, colds and influenza-like illnesses were common and associated with significant numbers of bed days, reduced activity days, school and work loss, impaired school performance, and increased health care utilization. Efforts to prevent upper respiratory illnesses among college and university students could improve their health and reduce health care utilization during the winter months.

Lead levels in high-risk and low-risk young children in the Minneapolis-St Paul metropolitan area

OBJECTIVES

To determine distribution of lead levels among children in a low-risk area; to validate a prescreening questionnaire; and to determine if universal lead screening is necessary in children in this area.

DESIGN

Blood lead levels and questionnaires were obtained on eligible patients. Data were analyzed using stepwise regression analysis.

SETTING

Community clinics and a health maintenance organization (HMO) in the Minneapolis-St Paul metropolitan area.

PATIENTS

A total of 9603 children at well-child visits, age 6 months to 6 years at community clinics, and 6 months to 3 years at the HMO.

OUTCOME MEASURES

Whole blood lead levels (WBLs) and questionnaires.

RESULTS

The total sample rate of WBLs at >/=10 microg/dL was 12%, at >/=15 microg/dL was 31/2%, and at >/=20 microg/dL was 1.2%. At both 10 microg/dL and 15 microg/dL, the non-HMO group was at higher risk. For both groups, risk factors included living in the central cities, and living in housing built before 1950. For the non-HMO group a history of the child eating paint chips, or the child or a sibling having previous lead poisoning were also risk factors.

CONCLUSIONS

Not all children need lead screening. Children living in the central cities, or with the risk factors of living in housing built before 1950 or a previous history of lead poisoning should be screened.