Functions of white blood cells

These depend on the cell type:

* Neutrophils phagocytose bacteria, fungi, protozoa, viruses, foreign cells, tumour cells and toxins. Chemotaxis occurs in response to activated complement proteins, cytokines and microbial products.

* Eosinophils phagocytose antigen-antibody complexes and larval forms of helminthic parasites. They inactivate mediators of anaphylaxis.

* Basophils possess IgE receptors and release mediators from granules in inflammatory and allergic reactions.

* Lymphocytes.

B lymphocytes synthesise antibodies (immunoglobulins), contributing to humoral immunity. In response to a specific antigen they give rise to a monoclonal proliferation of plasma cells, which produce specific antibodies. T lymphocytes, which comprise 65%-80% of circulating lymphocytes, are responsible for cell-mediated immunity. They mediate the cellmediated response to intracellular parasites, viruses, bacteria and fungi; delayed hypersensitivity; graft-versus-host reactions; and organ transplant rejection. They include subpopulations, which can be distinguished by cell surface markers.

Helper (CD4 marker): enhance antibody production by B cells and stimulate the activity of other T cells. Cytotoxic (CD8 marker): kill virus infected and tumour cells, based on previous experience. Suppressor: block helper T cells.

* Monocytes are phagocytic and become macrophages in the tissues. Macrophages occur in the following locations:

Connective tissues: histiocytes

Liver: Kupffer cells

Lungs: alveolar macrophages

Lymph nodes: free and fixed macrophages

Spleen: free and fixed macrophages

Bone marrow: fixed macrophages Skin: Langerhans cells; histiocytes Serous fluids: pleural and peritoneal macrophages

Was this article helpful?

0 0
Wake Up Now

Wake Up Now

For Those Who Can’t Wake Up On Time And Fatigue Throughout The Day. Now You Can Wake Up Early And Be Super Energetic Everyday.

Get My Free Ebook

Post a comment