Final answer:
Auto-reactive lymphocytes can be initially generated in primary lymphoid organs, but mechanisms such as central tolerance aim to eliminate or inactivate them to prevent autoimmune reactions. Lymphocytes mature and develop in primary lymphoid organs, and only those activated by external antigens participate in a polyclonal response to fight infections.
Step-by-step explanation:
Lymphocytes, including B cells and T cells, undergo maturation processes in primary lymphoid organs, primarily the bone marrow and thymus gland. During this maturation, they learn to distinguish between self and non-self. However, auto-reactive lymphocytes, which might attack the body's own cells, can occasionally emerge. To prevent autoimmunity, mechanisms such as central tolerance in the bone marrow help eliminate or deactivate these potentially harmful B cells through apoptosis or clonal anergy. The T cells undergo a similar selection process in the thymus. Peripheral tolerance also plays a role in ensuring auto-reactive lymphocytes do not cause harm once they have left the primary lymphoid organs. Only lymphocyte clones with receptors activated by an external antigen are stimulated to proliferate and mount an immune response, leading to a polyclonal response. This response generates large numbers of specific lymphocytes that fight off an infection without targeting the body's own tissues.