ABSTRACT
The expression of CD13 appears first, followed by acquisition of CD33 and increased expression of both CD13 and CD33. Hematopoietic cell differentiation starts from pluripotent stem cells and hematopoietic progenitor and precursor cells that become recruited and activated by cytokines and stromal cell signals, to differentiate into lymphoid or myeloid cells. CD13 and CD33 are expressed at all stages of maturation with CD13 being brightly expressed by blasts and neutrophils and dimly by metamyelocytes, and CD33 showing slight decrease in the intensity of CD33 expression as the cells become more mature. T-cell Differentiation T-cells arise from bone marrow progenitor T-cells (prothymocytes) that undergo maturation in the thymus and later in peripheral lymphoid tissues. The earliest definite T-cells evolve in the subcapsular region of the thymic cortex and are referred as triple-negative cells, due to lack of expression of CD4, CD8, and surface CD3.
