Improving the Analysis of T Cell Movement

Vaccine-induced T cells play an important role in combating malaria by eliminating infection in the liver stage. However, as millions of hepatocytes inhabit a mouse liver and only some are infected, how T cells locate the infection site and eliminate infection remains poorly understood. Are T cells moving intentionally toward parasites, or randomly successful? To answer this, I used timed position data of malaria-specific T cells, non-specific control T cells, and a parasite, obtained from experiments in a mouse liver; I performed analyses with the null hypothesis that T cells move randomly. I used two metrics, based on distances from the parasite and turning angles. The tests performed with these metrics did not suggest the same conclusions. Investigating this inconsistency, I calculated the probability of a cell getting closer to the parasite as viewed from the distance metric, which turned out less than the assumed 50 percent. With this discovery, I improved the null hypothesis' distribution. Applying this improvement to the original tests, the distance metric's test results more resembled the angle metric's. This development regarding the definition of random movement gets us one step closer to accurately analyzing cell position data and understanding T cell movement.