Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content ++ INTRODUCTION ++ Monocytes in the blood are in transit. They function in the tissues, where they mature into macrophages and participate in: — Inflammation, including granulomatous reactions, atheroma formation, and tissue repair. — Immunologic reactions, including delayed hypersensitivity. — Reactions to neoplasia and allografts. The need for macrophages in tissues also can be met by local proliferation of macrophages, not requiring increased transit of blood monocytes. Ninety percent of blood monocytes intensely express CD14 (lipopolysaccharide receptor) but not CD16 and 10 percent have weak expression of CD14 and strongly express CD16. Older persons have a striking decrease in the proportion of CD14+CD16– to CD14+CD16+ monocytes compared with younger persons. Disorders rarely produce abnormalities of monocytes alone in the absence of other blood cell abnormalities. ++ NORMAL BLOOD MONOCYTE CONCENTRATION ++ The monocyte count averages 1.0 × 109/L in neonatal life, gradually decreasing to a mean of 0.4 × 109/L in adult life. Monocytosis (in adults): >0.8 × 109/L. Monocytopenia: <0.2 × 109/L. ++ HEMATOLOGIC DISORDERS ASSOCIATED WITH MONOCYTOSIS ++ See Table 36–1. ++Table Graphic Jump LocationTABLE 36–1DISORDERS ASSOCIATED WITH MONOCYTOSISView Table|Favorite Table|Download (.pdf) TABLE 36–1 DISORDERS ASSOCIATED WITH MONOCYTOSIS Hematologic disorders Myeloid neoplasms Myelodysplastic states Acute monocytic leukemia Acute myelomonocytic leukemia Acute monocytic leukemia with histiocytic features Acute myeloid dendritic cell leukemia Chronic myelomonocytic leukemia Juvenile myelomonocytic leukemia B. Infections Chronic myelogenous leukemia (m-BCR–positive type) Polycythemia vera Chronic neutropenias Drug-induced neutropenia Postagranulocytic recovery Lymphocytic neoplasms B-cell Lymphoma T-cell Lymphoma Hodgkin disease Myeloma Macroglobulinemia Drug-induced pseudolymphoma Immune hemolytic anemia Idiopathic thrombocytopenic purpura Postsplenectomy state Inflammatory and Immune Disorders Connective tissue diseases Rheumatoid arthritis Systemic lupus erythematosus Temporal arteritis Myositis Polyarteritis nodosa Sarcoidosis Infections Mycobacterial infections Subacute bacterial endocarditis Brucellosis Dengue hemorrhagic fever Resolution phase of acute bacterial infections Syphilis Cytomegalovirus infection Varicella-zoster virus Gastrointestinal disorders Alcoholic liver disease Inflammatory bowel disease Sprue Nonhematopoietic malignancies Exogenous cytokine administration Myocardial infarction Cardiac bypass surgery Miscellaneous conditions Tetrachloroethane poisoning Parturition Glucocorticoid administration Depression Thermal injury Marathon running Holoprosencephaly Kawasaki disease Wiskott-Aldrich syndrome Source: Williams Hematology, 8th ed, Chap. 71, Table 71–1, p. 1042. ++ Neoplastic or Clonal Monocytic Proliferations ++ Oligoblastic myelogenous leukemia (refractory leukemia with excess blasts or myelodysplastic syndrome). Acute myelogenous leukemia (myelomonocytic or monocytic types). Chronic myelomonocytic leukemia. Juvenile myelomonocytic leukemia Unusual type of BCR-ABL (p190)-positive chronic myelogenous leukemia with monocytosis. ++ Reactive (Nonclonal) Monocytic Proliferations ++ Neutropenic states: cyclic neutropenia; chronic granulocytopenia of childhood; familial benign neutropenia; infantile genetic agranulocytosis; chronic hypoplastic neutropenia. Drug-induced agranulocytosis (transient monocytosis, especially in the recovery phase). Chlorpromazine toxicity, monocytosis precedes the agranulocytosis. Lymphoma. Hodgkin lymphoma. Postsplenectomy state. Myeloma. ++ INFLAMMATORY AND IMMUNE DISORDERS ASSOCIATED WITH MONOCYTOSIS ++ See Table 36–1. ++ Collagen Vascular Diseases ++ Rheumatoid arthritis. Systemic lupus erythematosus.... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. What is MyAccess? Create a FREE MyAccess profile to: Use this site remotely Bookmark your favorite content Track your self-assessment progress and more!