Blood and Immune Cells

Blood, the medium that facilitates the transport of nutrients, gases, and wastes throughout the body, is also home to the diverse cell types of the immune system. In humans and other vertebrates, blood and immune cells are suspended in plasma along with other proteins, minerals, carbohydrates and hormones. A typical microliter of blood may contain between 4-6 million red blood cells (erythrocytes), 4,000-11,000 white blood cells (leukocytes), and 200,000-500,000 platelets (thrombocytes). Erythrocytes mainly bind oxygen and deliver it to the body’s tissues. Leukocytes play an important role in the immune system and comprise of neutrophils, eosinophils, basophils, lymphocytes, and monocytes. Lymphocytes, like T cells and B cells, constitute a major component of the adaptive immune system. Platelets facilitate blood clotting and wound healing. Blood cells are also often categorized by density in gradient centrifugation (including PBMCs), or by expression of phenotypic cellular markers, such as CD proteins and other cell surface antigens.

Recommended Reading:

A Guide to T Cell Markers

The growing success of immunotherapies have deepened our understanding of the complexities of T lymphocytes, or T cells. These immune cells comprise many subsets and can be categorized by certain properties. This article will review phenotypic markers that have been used to identify various T cell types.
A Guide to B Cell Markers

B cells, or B lymphocytes, are an important and complex cell type that plays central roles in humoral immunity against infections, autoimmunity and transplantation. Extensive research in mice and humans has led to the identification of unique B cell populations, each with important implications in immunity. In this article, we review common B cell markers that have been recently described.
A Guide to Monocyte Markers

Monocytes, which comprise up to 10 percent of leukocytes in the blood, play essential roles in development, homeostasis, and immunity. Monocyte biology is fundamental in understanding not only infection response, but also in the longer term effects of inflammation. This article highlights common monocyte markers that have been mentioned in the literature.