Haptens: Small antigenic determinants capable of eliciting an immune response only when coupled to a carrier. Haptens bind to antibodies but by themselves cannot elicit an antibody response.Dinitrobenzenes: Benzene derivatives which are substituted with two nitro groups in the ortho, meta or para positions.Dermatitis, Contact: A type of acute or chronic skin reaction in which sensitivity is manifested by reactivity to materials or substances coming in contact with the skin. It may involve allergic or non-allergic mechanisms.Antibodies, Catalytic: Antibodies that can catalyze a wide variety of chemical reactions. They are characterized by high substrate specificity and share many mechanistic features with enzymes.Dinitrophenols: Organic compounds that contain two nitro groups attached to a phenol.Oxazolone: Immunologic adjuvant and sensitizing agent.Dinitrofluorobenzene: Irritants and reagents for labeling terminal amino acid groups.NitrobenzenesBinding Sites, Antibody: Local surface sites on antibodies which react with antigen determinant sites on antigens (EPITOPES.) They are formed from parts of the variable regions of FAB FRAGMENTS.Trinitrobenzenes: Benzene derivatives which are substituted with three nitro groups in any position.Nitrohydroxyiodophenylacetate: Also called 4-hydroxy-3-iodo-5-nitrophenylacetate. A haptenic determinant that can be radiolabeled and used as salts and derivatives for investigations of immunogenic specificity studies.gamma-Globulins: Serum globulins that migrate to the gamma region (most positively charged) upon ELECTROPHORESIS. At one time, gamma-globulins came to be used as a synonym for immunoglobulins since most immunoglobulins are gamma globulins and conversely most gamma globulins are immunoglobulins. But since some immunoglobulins exhibit an alpha or beta electrophoretic mobility, that usage is in decline.Antigen-Antibody Reactions: The processes triggered by interactions of ANTIBODIES with their ANTIGENS.Antibody Formation: The production of ANTIBODIES by proliferating and differentiated B-LYMPHOCYTES under stimulation by ANTIGENS.p-Azobenzenearsonate: A hapten capable of eliciting both antibody formation and delayed hypersensitivity when bound to aromatic amino acids, polypeptides or proteins. It is used as an immunologic research tool.Antibodies, Bispecific: Antibodies, often monoclonal, in which the two antigen-binding sites are specific for separate ANTIGENIC DETERMINANTS. They are artificial antibodies produced by chemical crosslinking, fusion of HYBRIDOMA cells, or by molecular genetic techniques. They function as the main mediators of targeted cellular cytotoxicity and have been shown to be efficient in the targeting of drugs, toxins, radiolabeled haptens, and effector cells to diseased tissue, primarily tumors.Antibodies: Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).Myeloma Proteins: Abnormal immunoglobulins characteristic of MULTIPLE MYELOMA.NitrophenolsAntibody Specificity: The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site.HemocyaninPhenylacetates: Derivatives of phenylacetic acid. Included under this heading are a variety of acid forms, salts, esters, and amides that contain the benzeneacetic acid structure. Note that this class of compounds should not be confused with derivatives of phenyl acetate, which contain the PHENOL ester of ACETIC ACID.Antibody-Producing Cells: Cells of the lymphoid series that can react with antigen to produce specific cell products called antibodies. Various cell subpopulations, often B-lymphocytes, can be defined, based on the different classes of immunoglobulins that they synthesize.Hemolytic Plaque Technique: A method to identify and enumerate cells that are synthesizing ANTIBODIES against ANTIGENS or HAPTENS conjugated to sheep RED BLOOD CELLS. The sheep red blood cells surrounding cells secreting antibody are lysed by added COMPLEMENT producing a clear zone of HEMOLYSIS. (From Illustrated Dictionary of Immunology, 3rd ed)Serum Albumin, Bovine: Serum albumin from cows, commonly used in in vitro biological studies. (From Stedman, 25th ed)Epitopes: Sites on an antigen that interact with specific antibodies.Antigens: Substances that are recognized by the immune system and induce an immune reaction.Azo CompoundsImmunoglobulin Fab Fragments: Univalent antigen-binding fragments composed of one entire IMMUNOGLOBULIN LIGHT CHAIN and the amino terminal end of one of the IMMUNOGLOBULIN HEAVY CHAINS from the hinge region, linked to each other by disulfide bonds. Fab contains the IMMUNOGLOBULIN VARIABLE REGIONS, which are part of the antigen-binding site, and the first IMMUNOGLOBULIN CONSTANT REGIONS. This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN.Immunization: Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow).Antibody Affinity: A measure of the binding strength between antibody and a simple hapten or antigen determinant. It depends on the closeness of stereochemical fit between antibody combining sites and antigen determinants, on the size of the area of contact between them, and on the distribution of charged and hydrophobic groups. It includes the concept of "avidity," which refers to the strength of the antigen-antibody bond after formation of reversible complexes.Mice, Inbred BALB CCross Reactions: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.Dinitrochlorobenzene: A skin irritant that may cause dermatitis of both primary and allergic types. Contact sensitization with DNCB has been used as a measure of cellular immunity. DNCB is also used as a reagent for the detection and determination of pyridine compounds.Langerhans Cells: Recirculating, dendritic, antigen-presenting cells containing characteristic racket-shaped granules (Birbeck granules). They are found principally in the stratum spinosum of the EPIDERMIS and are rich in Class II MAJOR HISTOCOMPATIBILITY COMPLEX molecules. Langerhans cells were the first dendritic cell to be described and have been a model of study for other dendritic cells (DCs), especially other migrating DCs such as dermal DCs and INTERSTITIAL DENDRITIC CELLS.Irritants: Drugs that act locally on cutaneous or mucosal surfaces to produce inflammation; those that cause redness due to hyperemia are rubefacients; those that raise blisters are vesicants and those that penetrate sebaceous glands and cause abscesses are pustulants; tear gases and mustard gases are also irritants.