Despite many efforts, HIV-1 infection remains a global health problem; an effective vaccine
would provide the best chance of controlling the pandemic. Recently, HIV vaccine research
has been focusing on the gut mucosal immune system and early immunological events, which
may set the stage for the later appearance of clinical immunodeficiency.
This thesis describes a method to obtain mucosal tissue, isolate mucosal mononuclear cells
(MMC) and study degranulation and intracellular cytokine memory responses using
polychromatic flow cytometry. Consistent and reproducible data were generated by adhering
to validated Standard Operating Protocols (SOPs). Qualification of such methods is essential
for use in vaccine clinical trials. Differences between the magnitude of single CD8 cytokine
and degranulation responses between blood and gut were seen; however, the quality of T cell
responses at the single cell level was remarkably similar in both compartments. Differences
between small bowel and colon were also described and introduce another layer of
complexity in the interpretation of mucosal responses to HIV-1. Differences in memory
phenotypes and function between blood and gut, in addition to small and large bowel allow
for better characterization of the cytotoxic potential of CD8+ and CD4+ T cells against HIV-1
infected cell targets. Finally, a significant positive correlation between IFNγ and
degranulation responses were seen with the frequencies of central memory and granzyme B-containing
CD8+ in the mucosa, but not in the blood. A better understanding of memory
responses and cytotoxic potential against HIV-1 targets will be important in vaccine research;
it may also help reshaping the current practice of empirically and unselectively fast-tracking
potential immunogens to large-scale trials.