Section 2: Cells of the Immune System

Where do all leukocytes originate?

Bone marrow, as pluripotent stem cells.

What are the two main categories of WBCs?

Granulocytes (contain granules) and agranulocytes (no granules).

Name the granulocytes.

Mast cells, neutrophils, basophils, eosinophils.

Name the agranulocytes.

Monocytes (become macrophages/dendritic cells), lymphocytes.

What do mast cells do?

Found in tissues, trigger local inflammatory and allergic responses.

What are neutrophils known for?

Phagocytic, short-lived, circulate in blood, migrate to tissue.

What is the function of basophils?

Involved in inflammatory and allergy responses.

What are eosinophils important for?

Inflammation and parasitic infections (protozoans, helminths).

What do monocytes become?

Dendritic cells or macrophages.

Give examples of tissue macrophages.

Kupffer cells (liver), alveolar macrophages (lungs), Langerhans cells (skin), microglia (brain).

What is unique about dendritic cells?

Have long extensions, derived from monocytes, bridge innate and acquired immunity, process foreign matter.

What are the two main types of lymphocytes?

B lymphocytes (B cells) and T lymphocytes (T cells).

Where do B cells originate and mature?

Originate and mature in bone marrow.

What do plasma cells do?

Produce antibodies.

Where do T cells mature?

In the thymus.

Name two functions of T cells.

Directly kill cells (cytotoxic T cells, Natural Killer T cells) or help other immune cells (T helper cells).

What do platelets do?

Function in blood clotting, inflammation, destruction of blood-borne pathogens.