T CELL RESPONSE AGAINST THE CYTOMEGALOVIRUS PROTEINS pp65 and IE1.

2.3
#57
T CELL RESPONSE AGAINST THE CYTOMEGALOVIRUS PROTEINS pp65 and IE1.
Maria P. Bettinotti, PhD , Scott Solomon MD , Minoo Battiwala MD , Nancy Hensel , Klodin Ghazarian , David Stroncek MD and John Barrett MD . Bethesda MD, National Institutes of Health, 20892, Department of Transfusion Medicine, Clinical Center and Bethesda MD, National Institutes of Health, 20892, Stem Cell Transplantation Section, Hematology Branch, NHLBI .

Cytomegalovirus (CMV) remains a significant problem following hematopoietic stem cell transplantation (HSCT). The cellular arm is the major component of the immune response against this virus. In this study we investigated the T cell response against the CMV proteins pp65 and IE1 in normal individuals to provide a baseline for the assessment of donor immunization in a future vaccination protocol with a vector encoding the pp65 protein, the major T cell target antigen.
We measured the immune response of 20 CMV-seropositive normal individuals, at 5 time points over a 2-month period and 6 seronegative individuals at one time point. Gamma interferon (IFN-γ) production was measured in peripheral blood monocuclear cells (PBMC) after stimulation with a cocktail of 15-mer peptides overlapping in 11 residues and covering the pp65 and IE1 proteins. PBMC corresponding to each individual were tested in parallel. After peptide stimulation, iFACS was performed using monoclonal antibodies against IFN-γ, CD3, CD4 and CD8, to provide a profile of the population of active cells.
All seronegative donors tested negative. One seropositive donor was negative for both proteins. The rest had a positive T cell population either against pp65 or IE1 or both and the results were consistent at different time-points. The percentages of IFN-γ producing CD8 or CD4 cells ranged from 0.1 to 3%. DNA typing for HLA class I and class II revealed a wide variety of alleles in the subjects studied, including those most common in the Caucasian population.
In conclusion, this study provides a baseline of the T cell response against pp65 and IE1 CMV proteins that can used as a foundation for vaccination protocols for HSCT donors.