Blood cell differentiation
WBC differential from highest to lowest
Monocytes (including lymphocytes, 3-7%)
Anucleate, biconcave=> large surface area: volume ratio=> easy gas exchange (O2 and CO2). Source of energy-glucose (90% anaerobically degraded to lactate, 10% of HMP shunt). Membrane contains the chloride-bicarbonate antiport important in the "physiologic chloride shift," which allows the RBC to transport CO2 from the periphery to the lungs for elimination. Survival time-120 dayse
Erythrocytosis=polycythemia=increased number of red cells
small cytoplasmic fragment derived from megakaryocytes. Involved in primary homeostatis. When activated by endothelial injury, aggregates with other platelets and interacts with fibrinogen to form hemostatic plug. Contains dense granuels (ADP, calcium) and alpha-granules (vWF, fibrinogen). Approximately 1/3 of platelet pool is stored in the spleen. Life spand of 8-10 days.
promotes blood clotting and prevents leakage of RBCs from damaged vessels. thrombocytopenia or platelet dysfunction results in petechiae.
WF receptor: Gplb.
Fibrinogen receptor: Gpllb/llla
types: granulocytes (basophils, eosinophils, neutrophils) and mononuclear cells (monocytes, lymphocytes). Responsible for defense against infections. Normally 4000-10,000 per microliter.
acute inflammatory response cell. 40-75% WBCs. Phagocytic. Multilobed nucleus. Large, spherical azurophilic granules (lysosomes) contain hydrolytic enzymes, lysozyme, myeloperoxidase, and lactoferrin (binds iron and inhibits growth of phagocytosed bacteria and some fungi). Hypersegmented polys are seen in vitamin B12/folate deficiency.
2-10% of leukocytes. large, kidney-shaped nucleus. Extensive "frosted glass" cytoplasm. Differentiates into macrophages in tissues.
phagocytoses bacteria, cell debris, and senescent red cells and scavenges damaged cells and tissues. Long life in tissues. Macrophages differentiate from circulating blood monocytes. Activated by y-interferon. Can function as antigen-presenting cell via MHCII. CD14 is a cell surface marker form macrophages.
1-6% of all leukocytes. bilobate nucleus. packed with large eosinophilic granules of uniform size. defends agains helminthic infections (major basic protein). highly phagocytic for antigen-antibody complexes. Produced histaminase and arylsulfatase (help limit reaction following mast cell degranulation)
causes of eosinophilia
Collagen vascular diseases
Mediates allergic reaction. <1% of all leukocytes. bilobate nucleus. Densely basophilic granules containing heparin (anticoagulant), histamine (vasodilator) and other vasoactive amines, and leukotrienes (LTD4). found in blood
mediates allergic reaction. degranulation-histamine, heparin, and eosinophil chemotactic factors. can bind the Fc portion of IgE to membrane. Mast cells resemble basophils structurally and functionally but are not the same cell type. found in tissue
involved in type I hypersensitivity reactions. cromolyn sodium prevents mast cell degranulation (used from asthma prophylaxis)
professional (APCs). express MHC II and Fc receptor (FcR) on surface. Main inducers of primary antibody response
round, densely staining nucleus. Small amount of pale cytoplasm. B lymphocytes produce antibodyes. T lymphocytes manifest the cellular immune response as well as regulate B lymphocytes and macrophages.
Part of humoral immune response. Arises from stem cells in bone marrow. Matures in marrow. Migrates to peripheral lymphoid tissue (follicles of lymph nodes, white pulp of spleen, unencapsulated lymphoid tissue). When antigen is encountered, B cells differentiated into plasma cells and produce antibodies. Has memory. Can function as an APC via MHC II
Off-center nucleus, clock-face chromatin distribution, abundant RER and well developed Golgi aparatus. B cells differentiate into plasma cells, which produce large amounts of antibody specific to a particular antigen
mediates cellular immune response. Originates from stem cells in the bone marrow, but matures in the thymus. T cells differentiate into cytotoxic T cells (MHC I, CD8), helpter T cells (MHC II, CD4)< and suppressor T cells. CD28 (costimulatory signal) necessary for T-cell activation. The majority of circulating lymphocytes are T cells (*0%)