Simpsons Roasting on an Open Fire to waste money on getting his son Bart's tattoo removed. He decides to keep their financial troubles a secret and gets a job as a shopping mall Santa Claus, but later discovers that the job does not pay enough. Desperate for a miracle, Homer and Bart go to the dog-racing track on Christmas Eve in hopes of earning some money but end up adopting an abandoned greyhound, Santa's Little Helper. The episode was written by Mimi Pond, and it was directed by David Silverman. "Simpsons Roasting on an Open Fire" was nominated for two Emmy Awards in 1990, and has
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,