* Most abundant white blood cell

* Phagocytize bacteria and other foreign particles

* Release antimicrobial substances

* Play a role in inflammation

Lymphocytes

* B cells: Produce antibodies

* T cells: Kill infected cells and regulate immune responses

* Natural killer cells: Kill infected cells and tumor cells

Monocytes

* Phagocytize bacteria and other foreign particles

* Differentiate into macrophages and dendritic cells

* Macrophages: Phagocytize bacteria, viruses, and other foreign particles

* Dendritic cells: Present antigens to T cells and stimulate immune responses

Eosinophils

* Attack parasitic worms

* Play a role in allergic reactions

Basophils

* Release histamine and other inflammatory mediators

* Play a role in allergic reactions

Platelets

* Play a role in blood clotting

* Release growth factors that help to repair damaged blood vessels