MTAP 2

• Immunology is the study of our immune system and can be defined as the study of a host’s reactions when foreign substances are introduced into the body.
• An antigen is a foreign substance that induces such an immune response.
• Immunity is all physiological mechanisms that endow the animal with the capacity to recognize the material as foreign to itself and to neutralize, eliminate, and metabolize them with or without injury to its own tissues.
• Factor B is not activated in the alternative pathway.
• The monomeric units of IgM are held together by S-S bonds.
• Antigens that trigger the formation of IgE include allergens and histamines.
• The C3 component has affinity for the IgA type of antibody.
• Naturally occurring antibodies found in saliva are primarily dimers.
• Types of immunity include Innate/Non-Adaptive/Non-specific/Natural, which is the ability of an individual to resist infections by means of normally present body functions, and Acquired/Adaptive/Specific, a reaction resulting from the invasion of foreign substance.
• Hallmark features of Adaptive Immunity include Mechanisms involved are non-specific, Reinforcement, Inducibility, Specificity, Components that are pre-formed, Non-adaptive; has a standardized magnitude response, Diversity, Memory, Lacks immunologic memory, Specialization, Self-limitation, and Discrimination.
• Types of Adaptive Immunity include Active, with previous exposure to an antigen, and Passive, without previous exposure to an antigen.
• Arms of Adaptive Immunity include Humoral, which is antibody-mediated immunity, and Cell, which is cellular immunity.
• Humoral immunity is mediated by antibodies in biologic fluid and involves direct cell to cell contact or soluble products secreted by cells.
• The degree of association between Ag-Ab reactions is affected by particle charge, electrolyte concentration and viscosity, antigen-to-antibody ratio, pH, temperature, and time.
• The antiglobulin test, also known as the AHG test or Coombs test, uses AHG as the bridge between cells coated with immunoglobulins that are unable to form cross links on their own.
• Agglutination inhibition is a method where soluble antigen from a patient sample combines with the reagent antibody so that there will be none left to react with particulate antigen, and is used in detection of secretor status.
• Lattice formation is the establishment of cross-links between sensitized particles and antibodies, also known as agglutination, which is a slower process than sensitization and is irreversible.
• Sensitization is the process where antibodies bind to antigens, forming a degree of association between them.
• Hemagglutination is a method where carrier RBCs are used, and can be of the direct, indirect, passive, or hemagglutination inhibition type.
• Passive agglutination is a method where antigen is attached to a carrier particle such as latex, and uses antigen coated particles for detection.
• Coagglutination is a method that uses bacteria as inert particles to which antibody is attached.
• Types of agglutination include direct agglutination, where the antigen is found naturally on the cell surface and agglutination of particulate Ag, where the reagent is antigen and the detected is antibody.
• Cellular immunity involves T lymphocytes and is mediated by cell-to-cell contact.
• Natural Active immunity can be acquired through previous infection to a certain antigen producing antibody against it, or artificially through vaccination.
• According to Sedimentation Constant, IgG is the smallest, most abundant, and readily diffusible immunoglobulin isoclass.
• IgE is the least abundant immunoglobulin isoclass.
• Serum IgA is lighter because it is monomeric.
• Complement-fixing antibodies fix complement.
• Immune Antibodies are formed when there is antigenic stimulation.
• IgM is the heaviest due to its pentameric structure.
• Isoantibodies/Alloantibodies are antibodies from the same species.
• Opsonins enhance phagocytosis.
• According to Temperature, cold antibodies (22 o C-25 o C) are IgM and warm antibodies (37 o C) are IgG.
• Secretory IgA is heavier because it is dimeric and possesses the J chain and the secretory component or secretory piece.
• Autoantibodies are a failure of immune tolerance.
• Blocking or inhibitory antibodies block or inhibit the action of antigens.
• Natural Antibodies are produced without apparent antigenic stimulation and are detected in newborns.
• Secretory IgA is not twice the molecular weight of serum IgA given that each unit of the dimeric secretory IgA is smaller, which may be the reason why it is not twice the molecular weight of its monomeric counterpart.
• Neutralizing antibodies neutralize toxins.
• Allergic antibodies react with allergens.