Paraneoplastic syndrome and host immune response .pptx

Pathology

1. H OST IMMUNE RESPONSE AND PARANEOPLASTIC SYNDROME (PNS) PRESENTED BY: SALAJ SONKAR(93)

2. HOST IMMUNE RESPONSE The host immune response is the body's defense mechanism against pathogens such as bacteria, viruses, fungi, and parasites. It consists of two main types:- Innate (nonspecific) immunity Adaptive (specific) immunity.

3. Innate (nonspecific) immunity Innate immunity is the first line of defence and responds rapidly to infections. It includes: Physical Barriers: Skin, mucous membranes, and secretions (e.g., saliva, tears) that physically block pathogens. Chemical Barriers: Enzymes and antimicrobial peptides in secretions that neutralize pathogens. Cellular Responses: Phagocytic Cells : Macrophages and neutrophils engulf and destroy pathogens. Natural Killer (NK) Cells : Target and kill infected or cancerous cells. Inflammatory Response: Increased blood flow, capillary permeability, and migration of leukocytes to the infection site, causing redness, heat, swelling, and pain.

4. Adaptive (specific) immunity Adaptive Immunityis more specific and develops over time. It involves the activation of lymphocytes and the production of antibodies. There are two main types: Humoral Immunity : Mediated by B cells that produce antibodies specific to the pathogen's antigens. Antibodies neutralize pathogens and mark them for destruction by other immune cells. Cell-Mediated Immunity : Involves T cells that recognize and kill infected cells. Helper T cells (CD4+) stimulate other immune cells, including B cells and cytotoxic T cells. Cytotoxic T cells (CD8+) directly kill infected cells.

5. Stages of immune response Recognition: Pathogens are recognized by pattern recognition receptors (PRRs) on immune cells or by specific antibodies. Activation: Signaling pathways activate immune cells, leading to the production of cytokines and other molecules that orchestrate the immune response. Response: Immune cells attack and eliminate the pathogen. Resolution: The immune response is downregulated to prevent excessive damage to the host tissues. Memory: Memory B and T cells remain in the body, providing long-term immunity against future infections by the same pathogen.

6. Disorders of Immune system Immunodeficiency: When the immune response is inadequate, leading to increased susceptibility to infections (e.g., HIV/AIDS). Autoimmunity: When the immune system attacks the body's own tissues (e.g., rheumatoid arthritis, lupus). Hypersensitivity: An exaggerated immune response to a harmless antigen (e.g., allergies, asthma). Understanding the host immune response is crucial for developing vaccines, treatments for infectious diseases, and managing immune-related disorders.

7. PARANEOPLASTIC SYNDROMES Paraneoplastic syndromes (PNS) are a group of conditions developing in patients with advanced cancer which are neither explained by direct and distant spread of the tumour , nor by the usual hormone elaboration by the tissue of origin of the tumour . About 10 to 15% of the patients with advanceed cancer develop one or more of the syndromes included in the PNS. The various clinical syndromes included in the PNS are briefly outlined here: i ) Endocrine syndrome Elaboration of hormones or hormone-like substances by cancer cells of non-endocrine origin is called as ectopic hormone production. origin is called as ectopic hormone production. Some examples are givenin next slide:

8. a) Hypercalcemia Symptomatic hypercalcemia unrelated to hyperparathyroidism is the most common syndrome in PNS. It occurs from elaboration of parathormone-like substance by tumors such as squamous cell carcinoma of the lung, carcinoma kidney, breast and adult T cell leukemia lymphoma. b) Cushing’s syndrome About 10% Patients Of Small cell carcinoma of the lung elaborate ACTH or ACTH-like substance producing Cushing’s syndrome. In addition, cases with pancreatic carcinoma and neurogenic tumours may be associated with Cushing’s syndrome. c) Polycythaemia Secretion of erythropoietin by certain tumours such as renal cell carcinoma, hepatocellular carcinoma and cerebellar haemangioma may cause polycythaemia. d) Hypoglycaemia Elaboration of insulin-like substance by fibrosarcoma , islet cell tumours of pancreas and mesothelioma may cause hypoglycaemia.

9. ii) Neuromyopathic syndromes About 5% of cancers are associated with progressive destruction of neurons throughout the nervous system without evidence of metastasis in the brain and spinal cord. iii) Effects on osseous, joints and soft tissue e.g. hypertrophic pulmonary osteoarthropathy and clubbing of fingers in cases of bronchogenic carcinoma. iv) Gastrointestinal syndromes Malabsorption of various dietary components as well as hypoalbuminaemia may be associated with a variety of cancers which do not directly involve small bowel. v) Renal syndromes Renal vein thrombosis or systemic amyloidosis may produce nephrotic syndrome in patients with cancer. vii) Cutaneous syndromes Characterized by the appearance of black warty lesions in the axillae and the groins may appear in the course of adenocarcinoma of gastrointestinal tract.

10. SUMMARY OF PNS