IMMUNOPATHOLOGICAL RESPONSE with TISSUE REACTIONS
Type II Hypersensitivity Reactions:
Humorally-Mediated Autoimmune Diseases
Interaction of cross-reactive antibody with host cell surface antigen; Autoantibodies and immune complexes
Cytotoxic reaction (antibody-mediated) (ADCC): Specific destructive action against certain cells presenting antigens from an invading agent
IMMUNOPATHOLOGICAL RESPONSE with TISSUE REACTIONS
Type III Hypersensitivity Reactions:
Immune Complex Reaction
Antibody-mediated
Deposition of circulating immune complexes in small vessels with complement activation causing damage to vessels
Serum sickness diseases
IMMUNOPATHOLOGICAL RESPONSE with TISSUE REACTIONS
Type IV Hypersensitivity Reactions:
Cell-Mediated Immune Response
T cells sensitized to “self” antigens secrete lymphokines that either do direct damage to host cells (e.g., TNF) or indirect damage enhancing the inflammatory response
Delayed-type hypersensitivity (TB test) (CD4+ mediated)
Cell-mediated cytotoxic diseases (CD8+ mediated)Granulomatous disease
HOST DEFENSE MECHANISMS
EXTERNAL (PRIMARY): Physical barrier of gross surface area; e.g., skin, respiratory tract, gastrointestinal tract, genitourinary tract
Mechanical and Physical Factors: sweat, fatty acids, pH, indigenous competitive flora (microbial antagonism), peristalsis, hair, cilia, urinary flushing, mucus, [tears, nasal secretions, saliva (lysozyme)], semen (spermine), mucosal secretory antibody (IgA predominant)
HOST DEFENSE MECHANISMS (cont.)
INTERNAL (SECONDARY): When an infecting parasite succeeds in penetrating the skin or mucuos membranes, cellular defense mechanisms include local macrophages and blood-borne phagocytic cells. Mononuclear phagocytes (monocytes and macrophages) and polymorphonuclear leukocytes (PMNs) are the most important phagocytic cells targeting bacterial infections.
MONONUCLEAR PHAGOCYTE SYSTEM (formerly Reticular Endothelial System): total pool of monocytes and cells derived from monocytes; predominantly macrophages (phagocytic cells)
HOST DEFENSE MECHANISMS (cont.)
OTHER:
NON-SPECIFIC: oxygen metabolites (superoxide anion radical, hydrogen peroxide, hydroxyl radicals, halide radicals), kinin forming system related to clotting
HOST-GENERATED PROTEINS: complex array of humoral and cellular mediators; e.g., lysosomal enzymes, lipid mediators, prostaglandins, histamine, heat- shock proteins (stress proteins)
HOST DEFENSE MECHANISMS (cont.)
CELLULAR IMMUNE RESPONSE: any immune
response directed at the cellular level; includes
INFLAMMATION and PHAGOCYTOSIS processes
INFLAMMATORY RESPONSE: a protective
response of tissues affected by disease or injury characterized by redness, localized heat, swelling, pain, and possibly impaired function of the infected part
PHAGOCYTOSIS: the process by which certain phagocytes can ingest extracellular particles by engulfing them; particles OPSONIZED with antibody are more rapidly and efficiently ingested
T-LYMPHOCYTES and CYTOKINES
HOST DEFENSE MECHANISMS (cont.)
HUMORAL IMMUNE RESPONSE: the sum total of
components of the immune response circulating in the blood or body fluids ; includes ANTIBODY and COMPLEMENT systems
COMPLEMENT PROTECTIVE SYSTEM: a protein
system in serum that combines with antibodies to form a defense against cellular antigens
B-LYMPHOCYTES and
ANTIBODY PRODUCTION: a class of proteins
produced as a result of the introduction of an antigen that has the ability to combine with the antigen that caused its production
