Final answer:
Multiple Sclerosis (MS) is likely initiated by CD4+ Th1 lymphocytes, which are involved in the adaptive immune response against intracellular pathogens and activate other immune cells, including B cells and CD8+ T cells.
Step-by-step explanation:
Multiple Sclerosis (MS) is an autoimmune disorder that affects the nervous system. The initiation of MS is complex and involves various cells of the immune system. Based on the information provided and the role of different cells in the immune response, CD4+ Th1 lymphocytes are associated with initiating a response against intracellular pathogens, which includes activating B cells and CD8+ T cells.
B cells are important in MS for the production of antibodies, while CD8+ T cells (cytotoxic T cells) kill infected cells. However, it's the CD4+ Th1 lymphocytes secreting cytokines that enhance the activity of other immune cells, which include B cells and CD8+ T cells in their effector functions, thus indicating the CD4+ Th1 lymphocytes' pivotal initiating role in conditions such as MS.
Natural killer cells, despite being a part of the innate immune response and having cytotoxic capabilities, are not primarily implicated in the initiation of MS. Therefore, with the information available, MS appears to be initiated by CD4+ Th1 lymphocytes.