Affinity purification:  A method used to separate a specific antibody from a mixture based on its specific affinity to an antigen. Antibody:  A class of glycoproteins present in the serum or tissue fluids in response to an immunogen, also known as immunoglobulin. Antigen:  Any molecule that binds specifically to an antibody. Antigen retrieval:  A method used to improve the binding of antibody to antigen in tissues or cells. Antiserum:  Refers to blood or serum from an immunized host containing antibodies of interest. Ascites fluid:  Fluid taken from the abdomen of a host animal containing unpurified monoclonal antibody produced by hybridoma cells. Chromatin immunoprecipitation (ChIP):  A method used to determine the location of DNA binding sites in the genome for proteins of interest such as transcription factors. Co-immunoprecipitation (Co-IP):  The use of an antibody to target and isolate a specific protein from a protein complex, thereby identifying unknown members of the complex, also known as protein complex immunoprecipitation. Conjugated antibody:  An antibody that is chemically bound to a reporter molecule such as a fluorochrome. Cross reaction:  Occurs when a part of the epitope of an antigen is shared with that of another antigen. Dot Blot: A method used to detect the presence of a substance. ELISA:  Enzyme-linked immunosorbent assays are used to detect the presence of a substance in a sample. Epitope (antigenic determinant):  The part of a substance which is recognized by antibodies, B cells or T cells. Flow cytometry (FC):  A method used to analyze cells or subcellular components using a flow cytometer. Fluorescence-activated cell sorting (FACS):  A specialized type of flow cytometry which is commonly used to sort cells from a heterogeneous mixture into separated containers based on recording of the light scattering and fluorescent signals that cells emit. Gel electrophoresis:  A technique used to separate DNA, RNA, or proteins by applying an electric field across a gel matrix. Host animals:  Animals that are immunized and then used to produce antibodies of interest. Hybridoma:  A type of cell made by the fusion of B cells and immortalized tumor cells; used to produce specific monoclonal antibodies. Immunofluorescence (IF): A method used to localize antigens in cells of a tissue section by using a fluorescent tag. Immunogen:  A specific type of antigen which is able to trigger an adaptive immune response if injected on its own. Immunohistochemistry (IHC):  A method used to localize antigens in cells of a tissue section. Immunoprecipitation (IP):  A method used to purify a protein or protein complex from a mixture. Monoclonal antibody:  A monospecific antibody originating from a single B cell type; usually produced from a single hybrid cell by fusion of a B cell with a tumor cell. Negative control:  Any tissue, cell, lysate or purified protein that is known not to contain the antigen of interest. Neutralization:  A neutralizing antibody is capable of binding the antigen and neutralizing the biological effects of the antigen. Polyclonal antibody:  A combination of antibodies from different B cells which recognize different epitopes of a specific antigen. Positive control:  Any tissue, cell, lysate or purified protein that is known to contain the antigen of interest. Primary antibody:  The antibody that directly binds to the antigen of interest. Radioimmunoassay (RIA): A method used to measure the amount of a substance through use of a radioactive label. RNA immunoprecipitation (RIP):  A method used to study the identity of RNA molecules which are precipitated along with RNA binding proteins. Secondary antibody:  The antibody that is used to bind the primary antibody. Western Blotting (WB):  A method used to detect specific antigens in a sample by applying gel electrophoresis techniques.