Final answer:
The question seems to be inquiring about a specific cell membrane marker lost during the maturation of T and B cells, which is not named in the references. The maturation process involves a series of selections, where self-reactive receptors are lost to prevent autoimmune diseases.
Step-by-step explanation:
The cell membrane marker that is lost during early maturation of T and B cells is not directly stated in the provided reference. However, the discussion of T cell development implies that the process of maturation involves changes to the cell surface markers. Mature T cells exhibit cell adhesion molecules known as either CD4 or CD8, which are critical for their function in the immune response. T cells, originating from multipotent hematopoietic stem cells in the bone marrow, undergo maturation where they lose any self-reactive receptors during the selection process in the thymus to prevent autoimmune responses.
B cell maturation similarly involves selection mechanisms in the bone marrow, leading to the removal of self-reacting B cells to avoid autoimmunity. Following the successful completion of their maturation process, B cells leave the bone marrow to continue maturation in the spleen and other lymphoid organs.