Solid organ transplant rejection: 3 categories depending on time between transplantation and rejectionoHyperacute: Immediate/rare d/t amount of pre transplant cross matching (HLA antigen antibody testing)- usually occurs in recipients with preexisting antibodiesto antigens (previous blood transfusions, previous grafts, women with multiple pregnancies develop antibodies against their husband’s HLA antigens)oAcute:Occurs within days-months. Develops immune response against unmatched HLAs. Sensitization usually initiated by recipient’s lymphocytes interacting with the donor’s dendritic cells within the transplanted tissue > induction of Th1 and Tc cells against donor’s antigens (can be seen on biopsy)oChronic: Occurs months-years. May be caused by inflammatory damage to endothelial cells lining blood vessels d/t weak cell-mediated immunologic reaction against minor histocompatibility antigens on grafted tissue.g.Describe the role of the human leukocyte antigen (HLA) in solid organ rejection. Human leukocyte antigen (HLA): Immune response against antigens on donated tissueoType IV cell mediated reaction (rejection within 2 weeks w/o immunosuppressive drugso**Matching HLA-DR locus appears to be most critical for graft acceptanceInfection ConceptInfection Process Description Colonization Germs found in the body that do not make you sick (No s/s)-can be transmitted in many ways direct contact, mechanical vectors (house flies), biologic vectors (lice, fleas, mosquitoes), direct exposure to contaminated materials (fecal-oral transmission through food/water (salmonella poisoning, hep A, cholera), human to human- droplet, direct contact (STIs, hep B, herpes), airborne transmissionInvasionOnce colonization has occurred the infectious disease agent can invade the surrounding tissue and other sites in the individual-Infectious agents have mechanisms that penetrate the tissues and evade the host’s non-specific and specific defenses (inflammation and immunity)MultiplicationCan undergo rapid multiplication with production of many new infectious progeny-Viral pathogens replicate within infected cells-Bacteria are intracellular pathogens, replicate in macrophages and other cellsSpread Some are highly invasive and may enter through lymphatics, blood, and internal organs-Successful spread relies on: adhesion molecules, toxins, protection against individual’s inflammatory & immune systems (rapid spread if immunocompromised)
ConceptDefinition Incubation periodWhen the pathogen begins active replication (initial colonization, begins multiplying)-No clinical manifestations-Highly dependent on the microorganism-Salmonella (6-8 hours), Hepatitis B (50-180 days)Prodromal stageCharacterized by initial appearance of clinical manifestations (mild)Invasion period Rapid multiplication of the organism & activation of the immune & inflammatoryresponses-Will begin having organism specific clinical manifestations & inflammation manifestationsConvalescent period Containment of infection
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