Lymphocytes vs Leucocytes
An adult has an average volume of 5dm3 of blood, which is a liquid tissue. In the plasma, blood cells are suspended. There are different types of blood cells that are making 45% of the volume of blood (Taylor et al, 1998). Those are red blood cells (erythrocytes), white blood cells and platelets, which are considered as cell fragments. White blood cells are called leucocytes, and there are two main groups of white blood cells. Those are polymorphonuclear leucocytes (Granulocytes), which makes 70% of white blood cells, and mononuclear leucocytes (Agranulocytes) making 28% of white blood cells (Taylor et al, 1998).
Leucocyte (white blood cells) is a collective term for the polymorphonuclear leucocytes (Granulocytes) and mononuclear leucocytes (Agranulocytes). These cells are larger than red blood cells and different from the red blood cell structure. They lack hemoglobin which is responsible for the red colour. White blood cells play an important role in defense mechanism, in the body. Either by ingesting foreign materials or producing antibodies, they protect the body from diseases. Having amoeboid movement, they are capable of squeeze through pores to reach infected tissues.
White blood cells have been further subdivided into two groups according to whether they have granules or not in their cytoplasm. So, Granulocytes, which have granules in their cytoplasm, have been further divided into neutrophils, eosinophils, and basophils. Each of this group has its own unique characteristics. Commonly, bone marrow is the origin of these three groups. Agranulocytes do not have granules in their cytoplasm having two subgroups called monocytes and lymphocytes.
Lymphocyte is white blood cell, which does not have granules in its cytoplasm; so, called as Agranulocytes. Of the white blood cells in the blood, 28% are Agranulocytes and 24% of Agranulocytes are lymphocytes. Thymus gland and lymphoid tissue produce lymphocytes by the cells originated in bone marrow. They have limited amoeboid movement (Taylor et al, 1998). The life time of these cells varies from a number of days up to more than ten years.
These cells have an important role in defense mechanism. They have three different types of cells. They are T type and B type and Natural killer (NK) cells. Both these T and B cells act on the specificity of alien substances such as microorganisms. For an example, producing antibodies or killing tumor cells and rejecting grafts they defend the body from infections. Natural killer cells also act on tumors and viral infections. Lymphocytes can be seen in central lymphoid tissues and organs such as tonsils, lymph nodes.
What is the difference between Leucocytes and Lymphocytes?
• Lymphocytes are type of leucocytes. Although lymphocytes have more similarities with leucocytes, lymphocytes have unique characteristics.
• Leucocytes possess relatively high percentage of blood while lymphocytes are vey small portion of the blood tissue.
• Some leucocytes have granules in their cytoplasm, whereas lymphocytes do not have granules in their cytoplasm.
• Lymphocytes have three subcategories; B cells, T cells, and Natural killer (NK) cells, but leucocytes have more sub categories.
• Leucocytes have different roles in defense mechanisms such as digesting bacteria, making anti histamine proteins, while these lymphocytes role is identifying the antigens and producing antibodies or killing tumor cells and rejecting grafts they defend the body from infections.
Taylor, D.J., Green N.P.O., Stout, G.W., (1998), Biological Science. Cambridge University Press, Cambridge
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