TAILIEUCHUNG - Chapter 061. Disorders of Granulocytes and Monocytes (Part 1)

Harrison's Internal Medicine Chapter 61. Disorders of Granulocytes and Monocytes Disorders of Granulocytes and Monocytes: Introduction Leukocytes, the major cells comprising inflammatory and immune responses, include neutrophils, T and B lymphocytes, natural killer (NK) cells, monocytes, eosinophils, and basophils. These cells have specific functions, such as antibody production by B lymphocytes or destruction of bacteria by neutrophils, but in no single infectious disease is the exact role of the cell types completely established. Thus, whereas neutrophils are classically thought to be critical to host defense against bacteria, they may also play important roles in defense against viral infections. . | Chapter 061. Disorders of Granulocytes and Monocytes Part 1 Harrison s Internal Medicine Chapter 61. Disorders of Granulocytes and Monocytes Disorders of Granulocytes and Monocytes Introduction Leukocytes the major cells comprising inflammatory and immune responses include neutrophils T and B lymphocytes natural killer NK cells monocytes eosinophils and basophils. These cells have specific functions such as antibody production by B lymphocytes or destruction of bacteria by neutrophils but in no single infectious disease is the exact role of the cell types completely established. Thus whereas neutrophils are classically thought to be critical to host defense against bacteria they may also play important roles in defense against viral infections. The blood delivers leukocytes to the various tissues from the bone marrow where they are produced. Normal blood leukocyte counts are x 109 L with neutrophils representing 45-74 of the cells bands 0-4 lymphocytes 1645 monocytes 4-10 eosinophils 0-7 and basophils 0-2 . Variation among individuals and among different ethnic groups can be substantial with lower leukocyte numbers for certain African-American ethnic groups. The various leukocytes are derived from a common stem cell in the bone marrow. Three-fourths of the nucleated cells of bone marrow are committed to the production of leukocytes. Leukocyte maturation in the marrow is under the regulatory control of a number of different factors known as colony-stimulating factors CSFs and interleukins ILs . Because an alteration in the number and type of leukocytes is often associated with disease processes total white blood count WBC cells per ill and differential counts are informative. This chapter focuses on neutrophils monocytes and eosinophils. Lymphocytes and basophils are discussed in Chaps. 308 and 311 respectively. Neutrophils Maturation Important events in neutrophil life are summarized in Fig. 61-1. In normal humans neutrophils are produced only in the bone

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