Glossary MO

• Oxidative burst: An increase in oxygen consumption in phagocytic cells, which generate oxygen radicals used to kill engulfed microorganisms.
• Opportunistic illnesses: Infections or malignancies that primarily occur in individuals who are immunocompromised
• Oncofetal antigens: Antigens that are expressed in the developing fetus and in rapidly dividing tissue, such as that associated with tumors, but that are absent in normal adult tissue
• Monoclonal gammopathy: A disorder in which a clone of lymphoid cells causes overproduction of a single immunoglobulin component called a paraprotein
• Occupational Safety and Health Administration (OSHA): A federal agency that monitors and enforces safety regulations for workers
• Oncogene: Gene that encodes a protein capable of inducing cellular transformation
• Ouchterlony double diffusion: A qualitative gel precipitation technique in which both antigen and antibody diffuse out from wells cut in the gel
• Mycelial fungi: Multicellular fungi that are made up of intertwined hyphae and reproduce through the production of spores
• Mycoses: Infections or Diseases produced by fungi
• Mumps virus: A single-stranded ribonucleic acid (RNA) virus that is the causative agent of mumps, a disease characterized by swelling of the parotid glands
• Monoclonal: Derived from a single clone of identical cells
• Multiplex immunoassay (MIA): An automated immunoassay that uses a mixture of polystyrene beads conjugated with different antigens or antibodies as the solid phase and a fluorescent-tagged antibody to simultaneously detect multiple antibodies or antigens in a sample by flow cytometry
• Multiple sclerosis (MS): An autoimmune disease in which the myelin sheath of axons becomes progressively destroyed by antibodies to myelin proteins
• Opsonization: Coating of a foreign antigen with antibody or complement to enhance phagocytosis
• Monocyte: The largest white blood cell (WBC) in peripheral blood
• Opsonins: Serum proteins that attach to a foreign substance and enhance phagocytosis (from the Greek word meaning “to prepare for eating”)
• Multiple myeloma: A malignancy of mature plasma cells that results in a monoclonal increase in an immunoglobulin component, most commonly IgG
• Monoclonal gammopathy of undetermined significance (MGUS): A premalignant plasma cell disorder characterized by the presence of monoclonal immunoglobulin in the serum, a plasma bone marrow count of less than 10%, and absence of clinical features
• Mycoplasma pneumoniae: A small gram-negative bacterium that lacks a cell wall and is the cause of upper respiratory infections
• Mutation: A permanent change in the nucleotide sequence within a gene or chromosome
• Myasthenia gravis (MG): An autoimmune disease characterized by progressive muscle weakness caused by formation of antibody to acetylcholine receptors
• Mutualistic: A relationship between a human host and microbial species in which both organisms benefit
• Molecular mimicry: The similarity between an infectious agent and a self - antigen that causes antibody formed in response to the former to cross-react with the latter.
• Monoclonal antibody: Very specific antibody derived from a single antibody-producing cell that has been cloned or duplicated
• Macrophage: A white blood cell (WBC) that engulfs and kills microbes and presents antigen to T cells
• Macrophage colony-stimulating factor (M-CSF): A cytokine that induces growth of hematopoietic cells destined to become monocytes and macrophages
• Major histocompatibility complex (MHC): The genes that control expression of a large group of proteins originally identified on leukocytes but now known to be found on all nucleated cells in the body
• MALDI-TOF: Matrix-associated laser desorption ionization time-of-flight mass spectrometry, a technique used to analyze proteins to identify a substance or microorganism in a sample
• Malignant: A descriptive term for cancerous tumors that can circulate to other parts of the body and invade nearby organs
• Mannose-binding lectin (MBL): A protein present in the blood that binds to mannose on bacterial cells and initiates the lectin pathway for complement activation
• Mast cell: A tissue cell that plays a role in allergic reactions
• Membrane attack complex (MAC): The combination of complement components C5b, C6, C7, C8, and C9 that becomes inserted into the target-cell membrane, causing lysis
• Membrane cofactor protein (MCP): A protein found on all epithelial and endothelial cells that helps to control complement-mediated lysis by acting as a cofactor for Factor I-mediated cleavage of C3b
• Memory cell: Progeny of an antigen-activated B or T cell that is able to respond to antigen more quickly than the parent cell
• Metastasis: Process of malignant cells traveling through the body, thereby causing new foci of malignancy
• MHC restriction: The selection of thymocytes that will only interact with the major histocompatibility complex (MHC) antigens found on host cells
• Microbiome: The collection of microorganisms that exists on the body, including bacteria, viruses, yeast, and fungi
• Micropipette: Mechanical pipette that delivers volumes in the microliter (μL) range; used when very small volumes are needed
• Microscopic agglutination test (MAT): A technique that is the gold standard for diagnosing leptospirosis
• Minor histocompatibility antigens (mHAs): Non-human leukocyte antigen (HLA) proteins that can induce a weak graft rejection response when introduced into an individual possessing a different polymorphic variant