DCs (big cells with dendrites: similar to a tree branch) are able to mobilize to put in contact with the CD4 T cells (smaller spherical cells). DCs touch different CD4 lymphocytes until they find those CD4s T cells specific for the microorganism that they are presenting in their membrane. When the CD4 lymphocyte learns that the body is infected it coordinates a strong response to eliminate the microorganism and cure the individual. This video relates to a paper that appeared in the Jan. 2, 2013, issue of Science Translational Medicine, published by AAAS. The paper, by F. García at University of Barcelona in Barcelona, Spain, and colleagues was titled, "A Dendritic Cell-Based Vaccine Elicits T Cell Responses Associated with Control of HIV-1 Replication."