Rishi Desai, MD, MPH

Transplant rejection

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TREATMENT MEDICATIONS  ▪ Glucocorticoids ▫ Subacute, chronic hypersensitivity ▪ Immunosuppression ▫ Refractory disease  SURGERY  ▪ Lung transplant ▫ Advanced chronic lung disease  OTHER INTERVENTIONS  ▪ Identify allergen, reduce/eliminate exposure → disease generally self-limiting (if acute) ▪ Occupational measures ▫ Reduce antigenic burden, moisture control, ventilation, personal protective devices (respirator masks)  Figure 33.2 A section of the lung of an individual with hypersensitivity pneumonitis. The alveolar septa are thickened and contain numerous lymphocytes.  TRANSPLANT REJECTION osms.it/transplant-rejection PATHOLOGY & CAUSES ▪ Transplanted tissue rejected (attacked) by new host’s immune system → destruction of transplanted tissue Timescale of rejection ▪ Hyperacute rejection ▫ Minutes after transplant ▫ Initiated by humoral immunity ▫ If tissue left implanted → systemic inﬂammatory response syndrome ▫ Often caused by preexisting anti-human leukocyte antibodies (HLA) ▪ Acute rejection ▫ Highest risk window one week to three months after transplant ▫ Mediated by cellular immunity ▫ Occurs in nearly all transplants if recipient inadequately immunosuppressed  208 OSMOSIS.ORG  ▫ Highly vascularised tissue (e.g. kidney, liver) esp. vulnerable ▫ Can be treated prior to organ failure; multiple episodes → chronic rejection ▪ Chronic rejection ▫ Months to years after transplantation ▫ Fibrosis of blood vessels → long term loss of function in transplanted organs Multiple divisions of immune system involved in rejection ▪ Innate immunity → attraction, activation of phagocytes ▪ Humoral immunity → activation of B cells → antibody secretion ▪ Adaptive response → cellular immunity → killer T cells induce apoptosis Cellular markers inﬂuencing rejection ▪ Blood group, major histocompatibility (MHC) antigens ▫ Most intense graft rejection reactions   