Which cells are associated with the CD19 marker?

The CD19 marker is specifically associated with B cells, which are a type of white blood cell involved in the adaptive immune response. CD19 is a surface protein expressed exclusively on B cells, beginning from the earliest stages of B cell development in the bone marrow and continuing through their maturation and activation processes. It serves as a pan-B cell marker, distinguishing B cells from other immune cell types.

In the context of immunophenotyping, the presence of CD19 is crucial for identifying and characterizing B cell populations in various clinical and research settings. Understanding the expression of CD19 can aid in diagnosing lymphoproliferative disorders like B cell leukemias and lymphomas, where CD19 can be used as a target for therapeutic monoclonal antibodies.

The other cell types listed do not express CD19. Cytotoxic T cells (which are involved in killing infected or cancerous cells), T helper cells (which assist other immune cells), and macrophages (which play roles in phagocytosis and immune activation) are associated with different surface markers specific to their lineage and function. Thus, they are not relevant in the discussion of CD19 and its association specifically with B cells.