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Lymphocytes

Type of lymphoid cells including B cells, T cells, and natural killer (NK) cells.

B cells

Lymphocytes that produce antibodies.

T cells

Lymphocytes involved in cell-mediated immunity.

Natural killer (NK) cells

Lymphocytes that play a role in the innate immune response.

Macrophages

Cells derived from monocytes that phagocytose pathogens and dead cells.

Antigen-presenting cells (APCs)

Cells, such as macrophages, that activate lymphocytes.

Dendritic cells

Cells that capture antigens and present them to T cells in lymph nodes.

Reticular cells

Cells that produce reticular fibers, forming supportive stroma in lymphoid organs.

Diffuse lymphoid tissue

Loosely organized lymphocytes and macrophages found in mucous membranes.

Lymphoid follicles (nodules)

Dense clusters of lymphocytes, containing germinal centers for B cell proliferation.

Bone marrow

Primary lymphoid organ where blood cell production and B cell maturation occur.

Thymus

Primary lymphoid organ where T cell maturation takes place.

Secondary lymphoid organs

Include lymph nodes, spleen, and mucosa-associated lymphoid tissue (MALT) like tonsils and Peyer’s patches.