Now, one very important type of T lymphocyte that we spoke about earlier is the helper T cell. So once infection begins, some of these T lymphocytes differentiate into our helper T cells. Now, what exactly is the purpose of helper T cells? Well, helper T cells help differentiate other cells of our immune system and they also release special types of chemicals known as interferons as well as interleukins. And these chemicals are involved in differentiating our cells as well as in promoting the process that defends our body from pathogens. For example, we know that helper T cells help differentiate the B lymphocytes into these plasma cells and memory B cells.