Research Project 1
We are using new molecular tools and methods including major histocompatibility complex (MHC) tetramer technology to quantify levels of CD8+ T cells specific for CMV in bone marrow and stem cell transplant donors and recipients. Our group prepares tetramer reagents that are used by us and by our collaborators to identify antigen-specific cells in human and mouse samples. We are also experimenting with combination of the tetramer assay with assays that examine aspects of cytotoxic T-lymphocyte function such as cytokine production and cell killing. One exciting new assay that has the potential to reveal information on the functionality of T-cells is the CD107 degranulation/mobilization assay recently described by Betts and colleagues at NIH. We have used this assay to examine the comparative functionality of T-cells recognizing different CMV antigens, and have reported some interesting antigen-specific differences in degranulation potential of CMV-specific CD8+ T-lymphocytes.
Our general objective is to determine which subsets of CMV-specific T cells are functional and important in clinical protection against CMV reactivation and disease. This information will be necessary to evaluate immune responses to CMV vaccines under development within the Laboratory of Vaccine Research. These studies are supported by a Leukemia and Lymphoma Society Translational Research Grant award to Dr. Lacey.
Degranulation/CD107a/b mobilization assay on two populations of CMV-specific T cells within PBMC from the same CMV-seropositive individual.
Research Project 2
BK virus (BKV) is a human polyomavirus related to SV40 and JC virus, and is an important pathogen that infects humans early in life, and establishes persistent infection of the human genitourinary tract. In healthy individuals the cellular arm of the immune system effectively controls the virus, and there are no clinical symptoms. However, in immunosuppressed kidney transplant recipients BKV commonly emerges from latency, and in a minority of persons can cause an invasive kidney infection known as BK virus nephritis (BKVN). This is an important clinical problem in KT recipients since it can lead to loss of the transplanted kidney and/or death.
A better understanding of how the immune system recognizes and controls BKV could allow us to design immunological probes that would permit the identification of kidney transplant recipients at risk of progression from BKV reactivation to BKVN, or at risk for development of BKVN, and offer the prospect of therapeutic immuno-interventions such as a vaccine against the virus. Our project is designed to provide this information, and is investigating BK virus (BKV)-specific cellular immune responses in a transgenic mouse model, in healthy donors, and in kidney transplant (KT) recipients.
In 2005 we described the first human T-cell epitope to be defined for BKV, and demonstrated that T-cells specific for this epitope cross-recognize antigens of the closely related JC virus, another important human pathogen. These studies are supported byThese studies are supported by a National Institute of Diabetes and Digestive and Kidney Diseases R21 award to Dr. Lacey.
Genome of BK virus, showing open reading frames.