Differences

Difference between white blood cells and lymphocytes

Are you a biology student? Do you enjoy learning about human biology? Do you need to learn the difference between white blood cells and lymphocytes and how they work? If so, then this blog is a must read. These are the first of many educational pieces that cover the human biology. This is the only blog around that talks about these two important concepts. I know a lot of you are biology students and may find this very useful.

There are many types of blood cells that we need to understand to know how our immune system functions. This blog will look at white blood cells, red blood cells and lymphocytes. This blog is meant to help students learn more about the different types of blood cells.

Major differences-white blood cells vs lymphocytes

Try to Understand:

White blood cells and lymphocytes are found in the blood of vertebrates. White blood cells are composed of granulocytes and non-granulocytes. There are three types of granulocytes in the blood. They are neutrophils, eosinophils, and basophils. 

Granulocytes are involved in host defense through innate immunity. Lymphocytes are non-granulocytes and are involved in adaptive immunity by producing specific antibodies against specific pathogens. Lymphocytes are composed of three types: T lymphocytes, B lymphocytes, and a null group containing natural killer cells and cytotoxic cells. 

The antigen presented by granulocytes is identified by T lymphocytes and activates B lymphocytes to produce specific antibodies. The main difference between white blood cells and lymphocytes is that white blood cells are all white blood cells in the blood, whereas lymphocytes are a type of blood cell involved in adaptive immunity in vertebrates .

In this article

1. What are white blood cells
– characteristics, structure, function
2. What are lymphocytes
– characteristics, structure, function
3. What is the difference between white blood cells and lymphocytes?

What are white blood cells?

What are white blood cells?

White blood cells are the only type of nucleated cells found in the blood that are involved in the defense of the host by destroying pathogens that invade the body of vertebrates. They are commonly called white blood cells. White blood cells can be divided into two groups, granulocytes and non-granulocytes, depending on the presence of granules in the cytoplasm. 

Three types of granulocytes, neutrophils, eosinophils, and basophils, can be found in the blood. Each of them has a different core shape and function within the body. The process of white blood cell formation is called hematopoiesis. During hematopoiesis, leukocytes differentiate from myeloblasts, lymphoblasts and monoblast stem cells.

Figure 1: Hematopoiesis

Neutrophils

Neutrophils

Neutrophils are professional phagocytes that destroy pathogens such as bacteria by phagocytosis. They contain a polylobed nucleus, usually composed of 2-5 lobes. The diameter of neutrophils is 8.85 µm. Neutrophils are the most abundant type of white blood cell. 40-75% of white blood cells are neutrophils. The normal range of eosinophils is 1,500-8,000 neutrophils per mm -3 . Neutrophils have a lifespan of 5 to 90 hours. 

Neutrophil granules contain lysozyme, phospholipase A2, acid hydrolase, myeloperoxidase, elastase, serine protease, cathepsin G, proteinase 3, proteoglycan, defensin, and bacterial permeability-increasing protein. Neutrophils are one of the first cells to migrate to the site of inflammation and respond to cytokines released by the inflamed cells. 

The process by which neutrophils move to the site of inflammation is called chemotaxis. Activated neutrophils generate neutrophil extracellular traps (NETs).

Eosinophils

Eosinophils

Eosinophils provide protection against parasites such as helm insects. The nucleus has two leaves in eosinophils. The diameter of eosinophils is 12-17 µm. 1-6% of white blood cells are eosinophils. The normal range of eosinophils is 0-450 eosinophils per mm -3 . Cytotoxicity is the process that eosinophils provide to prevent common hypersensitivity reactions. 

Cytotoxicity is mediated by cationic proteins contained in cytoplasmic granules. Granules contain histamine, RNase, DNase, eosinophil peroxidase, plasminogen, lipase, and major basic proteins. Basophils and mast cells also respond to allergic reactions. Eosinophils can also move to the tissue. Therefore, they are found in the thymus, spleen, ovaries, uterus, lymph nodes and lower gastrointestinal tract. 

The lifespan of eosinophils is 8-12 hours. In the organization, it is 8-12 days. It is produced by activation of eosinophils, cytokines such as TNF alpha and interleukins, growth factors such as TGF beta and VEGF, and other species.

Basophil

Basophil

Basophils and mast cells produce cytokines against parasites. The nucleus is bean-shaped in basophils. Basophils have a diameter of 10-14 µm. Basophils are the most common type of granulocytes in the blood. 0.5-1% of white blood cells are basophils. The normal range of basophils is 0-300 basophils mm -3 . Basophils have a lifespan of 60-70 hours. These cytokines provide protection against allergic inflammation. 

The granules contain histamine, proteolytic enzymes such as elastase and lysophospholipase, and proteoglycans such as heparin and chondroitin. Histamine and heparin in the granules prevent blood clotting in the circulation. 

Basophils also serve to provide protection against viral infections. Leukotrienes and some interleukins are secreted by activated basophils.

Monocyte

Monocyte

Monocytes are the only non-granulocytes found in white blood cells other than lymphocytes. They are involved in the intercellular killing of pathogens. They respond immediately before other WBCs invade the infected area. By translocation to inflamed tissue, monocytes can differentiate into macrophages. 

Macrophages are a type of professional phagocyte. Macrophages also present antigens on T lymphocytes and promote the generation of adaptive immune responses.

Other types of white blood cells are lymphocytes, which we will discuss in the following articles.

What are lymphocytes?

What are lymphocytes?

Lymphocytes are the last type of leukocyte and are primarily involved in adaptive immunity by producing specific antibodies against specific pathogens during host defense. During hematopoiesis, lymphocytes differentiate from lymphoblastic stem cells. The three major types of lymphocytes are T lymphocytes, B lymphocytes, and natural killer cells. T lymphocytes are involved in humoral immunity, and plasma cells differentiated from B lymphocytes secrete specific antibodies against specific pathogens.

Mature T lymphocytes express T cell receptors (TcRs) that are specific for a particular antigen. The CD3 molecule binds to the TcR and is expressed on the membrane. TcR / CD3 can identify antigens present in the MHC complex of infected cells. There are three types of T cells: T helper cells, T cytotoxic cells and T suppressor cells. T-helper cells affect B lymphocytes by activating B lymphocytes to produce specific antigens against specific pathogens. T cell-damaging cells are cytotoxic to tumor cells while presenting pathogen antigens along with MHC class I molecules. The response of T and B cells is suppressed by T suppressor cells.

Figure 2: T cell-dependent B cell activation

B lymphocytes are activated by T cells and the antibody IgM and are produced as primary immunity that can be identified in serum 3-5 days after infection. IgM levels peak 10 days after infection. B cells also present antigens for digested pathogens along with the MHC II complex. Some of the B cells become memory B cells, which preserve the memory of invading pathogens for a long period of time. Natural killer (NK) cells are granular lymphocytes that non-specifically phagocytose infected cells by viruses and tumor cells. Digestion of these cells by NK cells secretes IFN-γ and IL-2. NK cells express the surface receptor CD16. Activated NK cells also secrete INF-α and TNF-γ.

Natural killer cell

Difference between white blood cells and lymphocytes

correlation

White blood cells: White blood cells are all white blood cells in the blood.

Lymphocytes: Lymphocytes are a type of white blood cell in the blood that are primarily involved in adaptive immunity during host defense.

composition

White blood cells: White blood cells are composed of both granulocytes and non-granulocytes.

Lymphocytes: Lymphocytes are mainly composed of non-granulocytes.

type

White blood cells: White blood cells are composed of neutrophils, eosinophils, basophils, and lymphocytes.

Lymphocytes: Lymphocytes are composed of T lymphocytes, B lymphocytes, and a null group containing natural killer cells and cytotoxic cells.

Manufacturing

White blood cells: White blood cells are produced by either bone marrow stem cells or lymphoid progenitor cells.

Lymphocytes: Lymphocytes are produced by lymphoid progenitor cells.

Role in host defense

Leukocytes: Leukocytes are involved in both innate and adaptive immunity during host defense.

Lymphocytes: Lymphocytes are primarily involved in adaptive immunity during host defense.

Conclusion

White blood cells are white blood cells contained in the blood. Blood contains five major types of white blood cells. They are neutrophils, eosinophils, basophils, monocytes, and lymphocytes. Neutrophils, eosinophils, and basophils are granulocytes, and the granules contain various contents. They are primarily involved in innate immunity, and the host’s defense system produces the same immune response non-specifically against all pathogens. 

These granulocytes destroy pathogens such as bacteria, viruses, and parasites by pagocytosis. While destroying pathogens, they present the destroyed pathogen antigens on the cell membrane. Monocytes are a type of white blood cell without granules. However, monocytes function as professional phagocytes by differentiating into macrophages in inflamed tissue. 

The resulting antigen is recognized by T helper cells, causing B lymphocytes to produce specific antibodies against specific antigens. Therefore, lymphocytes are involved in the adaptive immunity of the host defense mechanism. Natural killer cells are a type of circulating lymphocyte that phagocytose virus-infected and tumor cells. They are a type of granulocyte. However, the main difference between white blood cells and lymphocytes is the type of immunity produced during host defense.

See also:
1. Goldman, Almond S. “Overview of Immunology”. Medical microbiology. 4th edition. National Library of Medicine, January 1, 1996. Web. April 5, 2017.

Image courtesy of:
1. “Illu blood cell lineage” via Commons Wikimedia (public domain)
2. “Activation of T-dependent B cells” by Altaileopard – own work via Commons Wikimedia (public domain)
3. by NIAID “Human Natural Killer Cell” (CC BY 2.0), via Flickr

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