FUNCTIONS OF LEUCOCYTES.pdf
- 1. FUNCTIONS OF LEUCOCYTES MOHIT BIJARANIA ROLL NO. : 53
- 2. INTRODUCTION ● Leucocytes are called white blood cells which are the mobile units of the body’s protective system. ● They are formed partially in bone marrow and partially in lymph tissues.
- 3. TYPES LEUCOCYTES GRANULOCYTES AGRANULOCYTES MONOCYTES LYMPHOCYTES EOSINOPHILS NEUTROPHILS BASOPHILS
- 4. 1. NEUTROPHIL(50-70%) ● They are first to do phagocytosis during bacterial infection by chemotaxis ● It contains fever producing substance, endogenous pyrogen which is an important mediator of fibril response to bacterial pyrogens ● Degranulation- The granules contain various proteases plus anti microbial proteins called defensins, this content is discharged into phagocytic vacuoles containing the bacteria and also into interstitial space, this is called degranulation FUNCTIONS
- 5. 2. EOSINOPHIL (1-4%) ● It releases enzymes such as histaminase at the site of allergic reactions, which limits the effects of inflammatory mediators. ● It provides local immunity because it is abundant in the mucosa of respiratory tract, gastrointestinal tract and urinary tract ● It releases chemicals like peroxidase that attack parasites that are too large to be engulfed by phagocytosis(helminth larvicidal) ● It interacts with T lymphocytes in allergy
- 6. 3. BASOPHIL (<0.5%) ● Basophils participate in immediate hypersensitivity reactions by releasing chemical mediators like ECFA to perform allergic manifestations, these range from mild urticaria(localised skin infections) to severe anaphylactic shocks ● It releases heparin which acts as anti-coagulant and activates lipoprotein lipase which facilitates consumption of triglycerides after meals ● Initiation of tissue repair after injury
- 7. 4. LYMPHOCYTES(20-40%) A. T- LYMPHOCYTES - Cellular immunity ● T Helper cells ● T cytotoxic cells ● T suppressor cells ● T memory cells B. B- LYMPHOCYTES- Humoral immunity ● Memory cell ● Plasma cell
- 9. 5. MONOCYTES(2-8%) ● Phagocytic action by chemotaxis thus it forms second line of defence after neutrophils ● It acts as an immunoregulator ● They secrete prostaglandins E and clot promoting factors and also factors that affect lymphocytes ● They play a key role in innate immunity ● They remain in blood for 72 hours and then enter into tissues forming macrophages
- 10. 6. MAST CELLS ● Their granules contain proteoglycans histamine and proteases which they de granulate when allergens bind to cell bound IgE molecules ● In acquired immunity, it releases TNF-α in response to bacterial products by an antibody independent mechanism