Biomedical subjects

Elizabeth Wolf

Publications and source records attributed to Elizabeth Wolf.

3 recordsLinked to original sources

PubMed2006

MHC class II expression identifies functionally distinct human regulatory T cells.

It has been known for decades that circulating human CD4 cells can express functional MHC class II molecules that induce T cell nonresponsiveness with Ag presentation. Because there is significant expression of MHC class II (MHC-II) determinants (DR) on a subpopulation CD4+ CD25(high) regulatory T cells (Treg), we examined the function of CD4 cells expressing MHC-DR. We demonstrate that MHC-II expression on human CD4+ CD25(high) T cells identifies a functionally distinct population of Treg that induces early contact-dependent suppression that is associated with high Foxp3 expression. In striking contrast, MHC-II- CD4+ CD25(high) Treg induce early IL-4 and IL-10 secretion and a late Foxp3-associated contact-dependent suppression. The DR expressing CD25(high) Treg express higher levels of Foxp3 message and protein, compared with the DR- CD25(high) Treg population. Direct single-cell cloning of CD4+ CD25(high) Treg revealed that, regardless of initial DR expression, ex vivo expression of CD25(high), and not DR, predicted which clones would exhibit contact-dependent suppression, high levels of Foxp3 message, and an increased propensity to become constitutive for DR expression. Thus, the direct ex vivo expression of MHC-II in the context of CD25(high) identifies a mature, functionally distinct regulatory T cell population involved in contact-dependent in vitro suppression.

Antigen Presentation↗

PubMed2005

Risk factors for experiencing psychosis during cocaine use: a preliminary report.

UNLABELLED: Cocaine induced psychosis (CIP) is a common, but not universal side effect of cocaine abuse. Factors underlying the development and severity of CIP remain poorly understood. This study tests the hypothesis that earlier age of initiation of regular use may increase the likelihood of developing CIP, or the severity of CIP symptoms. METHODS: Cocaine use history and severity of CIP (if any) were assessed with the Cocaine Experience Questionnaire in 51 abstinent (3 weeks-1 year) cocaine dependent individuals. Subjects were divided into those with high and low CIP severity, and into those with early age of initiation of regular cocaine use, and later age of initiation. Various cutoffs between early and late age of initiation were used, ranging from 15 to 22 years. RESULTS: From ages 17 through 20, controlling for cumulative duration of use, severity scores were significantly higher for the early initiation group than for the later initiation group (p values ranged from 0.031 to 0.036). Cumulative duration of use, but not age of initiation, significantly predicted initial development of CIP (p=0.044). CONCLUSIONS: The data suggest that early age of initiation of regular cocaine use occurring during vulnerable periods of brain development, may lead to increased severity of CIP.

Adult↗

PubMed2005

Functional analysis of highly defined, FACS-isolated populations of human regulatory CD4+ CD25+ T cells.

The importance of CD4+ CD25+ regulatory T cells (Treg) in maintaining immune homeostasis has been directly demonstrated in vivo by their manipulation in a number of autoimmune disease models in the mouse. In the study of human regulatory cells, we have found that the cells that consistently demonstrate the in vitro regulatory activity most similar to that described for murine cells in vitro are best identified by restricting the isolation of CD25+ CD4 T cells to those cells expressing only the highest levels of CD25, representing approximately 2-3% of total CD4 T cells. Thus, it is the CD4+ CD25high subset that exhibits the in vitro characteristics that are identical to the CD4+ CD25+ regulatory cells initially characterized in mice. Furthermore, the cells expressing medium to low levels of CD25 not only do not exhibit suppressive activity directly ex vivo, but also actually contain a significant proportion of CD62L- CD4 T cells which are believed to be in vivo activated T cells. Due to the inherent difficulties in using CD25 as a marker for the purification of Treg cells, the finding that selection of the CD25high subset of CD4+ CD25+ T cells minimizes the co-isolation of contaminating activated CD4 T cells is important for future studies of these Treg cells in human disease. In order to perform these studies, we first had to establish a highly reproducible 'micro in vitro co-culture' assay system to enable the functional analysis of high-purity, but low-yield regulatory populations derived from FACS sorting. With this system in place, we are poised to dissect the potential heterogeneity of mechanisms employed by highly specific subpopulations of CD4+ CD25+ cells.

Antigens, CD↗