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Principal Investigator: Dr. Donna Muscarella
Contact Information: E-mail: dem10@cornell.edu - Phone: 607-253-4047
Sponsor: Johns Hopkins Center/Alternatives to Animal Testing
Grant Number: N/A
Title: An In Vitro Model System to Evaluate Drug Effects on B-lymphocyte Survival and Antibody Production
Annual Direct Cost: $24,348
Project Period: 02/01/06-01/31/07
The production of the diverse repertoire of antibodies required to recognize foreign antigens is achieved by the selection of specific clonal populations of B-lymphocytes (B-cells). This fundamental process occurs within the germinal centers of lymph nodes and is dependent on specific survival signals generated within the germinal center. Such signals are derived, in part, by the association/adhesion of B-cells with follicular dendritic cells. Although animal models have been instrumental in identifying potentially immunotoxic chemicals, the basic mechanisms by which chemicals may specifically perturb the germinal center reaction, resulting in aberrant antibody production, are not understood.
Our experimental system is comprised of a panel of human B-cell lines that, when grown in a co-culture system with the human follicular dendritic cell line, HK, specifically adhere to the HK cells. These adhered cells show alterations in their propensity to undergo apoptosis induced by a variety of clinically important drugs and environmental chemicals. Importantly, the B-cell lines show differences in their sensitivity to apoptosis induction by chemicals due to the altered expression of genes encoding the Bcl-2 family of apoptosis-regulating proteins. These genes are also differentially expressed at specific stages of normal B-cell maturation within the germinal center. Thus, this model system will also allow us to identify combinations of normal physiological signals (i.e. adhesion to dendritic cells and expression of Bcl-2 proteins) that may modulate the sensitivity of susceptible and resistant B-cell populations to apoptosis induction by chemical/drug exposure.
We will use this system to examine the effects of potentially immunotoxic chemicals on essential processes in the germinal center reaction including: the interaction of B-cells with HK cells via specific surface receptors, the signaling pathways activated by surface-receptor engagement that control cell survival, and the role of mitochondrial function as a critical target of immunotoxic chemicals. This model system is expected to provide an alternative means to assess and predict the immunotoxic potential of drugs and chemicals on B-cell survival.
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