Santa's Little Helper backyard. In "Bart's Dog Gets an F" (season two, 1991), he manages to infuriate the entire family by destroying valued items in the home. As a result, Homer and Marge want to get rid of the dog, but Bart and Lisa convince them that he can be trained at an obedience school. Santa's Little Helper does not do well there as Bart is unwilling to use a choke chain suggested by the instructor. The night before the final exam, Bart and Santa's Little Helper play, thinking it will be their last few hours together. This bonding breaks down the communication
T helper cell because such knowledge may be very useful in the treatment of disease and in increasing the effectiveness of vaccination. Proliferating helper T cells that develop into effector T cells differentiate into two major subtypes of cells known as T1 and T2 cells (also known as Type 1 and Type 2 helper T cells, respectively). T1 helper cells lead to an increased cell-mediated response, typically against intracellular bacteria and protozoa. They are triggered by IL-12 and their effector cytokines are IFN-γ and IL-2. The main effector cells of T1 immunity are macrophages as well as CD8 T cells, IgG B cells,