TOPICS: Leukocyte count, leukopenia, leukocytosis, CD34+ hematopoietic stem cells, neutropenia, chemotherapy, alkylating agents, sepsis, aplastic anemia, GM-CSF, G-CSF, lymphopenia, DiGeorge syndrome, SCID, HIV/AIDS, Cushing's syndrome, exogenous steroid use, SLE, radiation therapy, eosinopenia, corticosteroids, neutrophilia, acute inflammation, left shift, band cells, metamyelocytes, leukoerythroblastic reaction, monocytosis, basophilia, eosinophilia, chronic myeloid leukemia, anaphylactic reaction, parasitic infections, hodgkin lymphoma, lymphocytosis, CD8+ T cell, Bordetella pertussis, infectious mononucleosis