Glossary SN

• Natural killer (NK) cell: A type of lymphocyte that has the ability to kill target cells such as tumor cells and virus-infected cells without prior exposure to them
• Negative predictive value: The probability that a person with a negative screening test does not have the disease being tested for
• Negative selection: The process by which T cells that can respond to self-antigen are destroyed in the thymus
• Neoplasm: An abnormal cell mass; a tumor
• Nephelometry: A technique for determining the concentration of particles in a solution by measuring the light scattered at a particular angle from the incident beam as it passes through the solution
• Neutrophil: A white blood cell (WBC) with a multilobed nucleus and a large number of neutral staining granules on a blood smear treated with Wright stain
• Its main function is phagocytosis
• Next-generation sequencing (NGS): A technique that is able to sequence large numbers of DNA templates simultaneously (massively parallel sequencing), yielding hundreds of thousands of short nucleotide sequences in a single run
• Noncompetitive immunoassay: An immunoassay in which patient antigen is captured by antibody bound to a solid phase and detected by subsequent addition of a labeled antibody
• The amount of label measured is directly proportional to the amount of patient antigen present in the test sample
• Non-Hodgkin or lymphocytic lymphoma (NHL): A wide range of cancers of the lymphoid tissue, of which B-cell lymphomas represent the majority
• Nontreponemal tests: Serological tests for syphilis that detect antibody to cardiolipin and instead of specific antitreponemal antibody
• Nucleic acid: A sequence of nucleotides that carries the genetic information for a protein; DNA or RNA
• Nucleolus: A prominent structure within the nucleus where transcription and processing of ribosomal ribonucleic acid (rRNA) and assembly of the ribosomes takes place
• Nucleosome antibodies: Autoantibodies against DNA – histone complexes [also known as nucleosomes or deoxyribonucleoprotein (DNP)].
• Nucleotide: A unit of DNA or ribonucleic acid (RNA) composed of a phosphorylated ribose or deoxyribose sugar and a nitrogen base
• S protein: A control protein in the complement cascade that interferes with binding of the C5b67 complex to a cell membrane, thus preventing cell lysis
• Safety data sheet (SDS): A document that contains information on physical and chemical characteristics of a substance, fire, explosion reactivity, health hazards, primary routes of entry, exposure limits and carcinogenic potential, precautions for safe handling, spill clean-up, and emergency first aid information
• Sandwich immunoassay: An immunoassay in which antibody to the target antigen is bound to the solid phase; also known as a capture or immunometric immunoassay
• Sarcoma: A type of cancer derived from bone or soft tissues such as fat, muscles, tendons, cartilage, nerves, and blood vessels
• Scarlet fever: An illness with a characteristic rash and fever that is caused by the erythrogenic toxins released from Group A streptococcal bacteria
• Six Sigma: A method employed by health-care organizations to reduce variables and decrease errors.
• Single-positive (SP) stage: A stage in T-cell development characterized by the presence of surface CD4 or CD8 but not both markers.
• Secondary lymphoid organs: Organs that include the spleen, lymph nodes, appendix, tonsils, and other mucosal-associated lymphoid tissue where the main contact with foreign antigens takes place.
• Seroconversion: Change of a serological test result from antibody negative to antibody positive from samples obtained during the course of an immune response.
• Single-parameter histogram: Plot of a chosen parameter or measurement on the x-axis against the number of events on the y-axis.
• Serum amyloid A (SAA): An acute-phase protein that acts as a chemical messenger to activate monocytes and macrophages in order to increase inflammation.
• Serological pipette: A graduated or measuring pipette that has marks all along its length all the way down to the tip.
• Sensitization: (1) The combination of antibody with a single antigenic determinant on the surface of a cell without agglutination.
• Sjögren’s syndrome: An autoimmune disorder characterized by the presence of dry eyes, dry mouth, and connective tissue disease.
• Serotype: A group of related bacteria or viruses that share specific antigens that can be identified by serological testing.
• Severe combined immunodeficiency (SCID): An inherited deficiency of both cell-mediated and antibody-mediated immunity that results in overwhelming infections and death in infancy if not treated successfully.
• Secondary immunodeficiency: An immunodeficiency that is acquired secondary to other conditions, such as certain infections, malignancies, autoimmune disorders, and immunosuppressive therapies.
• Side (right angle) scatter (SSc): Light scattered at 90 degrees in a flow cytometer that indicates the complexity of a cell, determined by characteristics such as granularity.
• Single step, competitive, immunochromatographic method: A rapid immunoassay in which antigen in a patient sample is added to a membrane containing detection antibody adsorbed onto colloidal gold particles.
• Single-nucleotide polymorphisms (SNPs): Variants of a particular DNA sequence involving a single base pair; these variations are shared by at least 2% of a population and result in the generation of different alleles.
• Serum: The liquid portion of the blood minus the clotting factors.
• Serial dilution: A method of decreasing the strength of an antibody solution by using the same dilution factor for each step.
• Shift: An abrupt change in the mean that may be caused by a malfunction of an instrument or a new lot number of reagents.
• Self-tolerance: The ability of the immune system to accept self-antigens and not initiate a response against them.