CD33 cells refer to a class of cells expressing the CD33 protein, which is a cell surface marker. In the context of human bone marrow, CD33 cells are mainly associated with myeloid cells, which include cells such as granulocyte precursors, monocytes and macrophages.

CD33 is a glycoprotein found on the surface of immature and mature myeloid cells. Its expression is often used as a marker to identify and isolate these cells in bone marrow.

Myeloid cells, including those expressing CD33, play a key role in the immune system by participating in phagocytosis of pathogens, antigen presentation and regulation of inflammation.

 Research on CD33 cells is continuing to gain a better understanding of their role in the bone marrow, as well as to explore new therapeutic approaches. Advances in our understanding of these cells could have important implications in the treatment of diseases related to the haematopoietic system.