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Host immune response and paraneoplastic syndrome
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- 2. NEOPLASM : Aneoplasm, commonly known as a tumor, is an abnormal growth of tissue that arises due to uncontrolled, excessive cellular proliferation. > The host immune response to neoplasms (tumors) involves a complex interplay between the immune system and cancer cells. This interaction is crucial for understanding how the body attempts to control or eliminate cancer, and how tumors can evade or suppress immune responses.
- 4. 3. IMMUNE RESPONSEMECHANISM Cell-Mediated Immunity:Involves CTLs and NK cells directly killing cancer cells. Humoral Immunity: Involves B cells producing antibodies against tumor antigens, facilitating immune cell recognition and destruction. Cytokine Production: Various cytokines (e.g., interferons, interleukins) enhance the immune response by activating and recruiting immune cells.
- 5. 4. TUMOUR EVASIONSTRATEGY Immune Checkpoint Molecules: Tumors may express proteins like PD-L1 that bind to inhibitory receptors (e.g., PD-1) on T cells, reducing their activity. Immunosuppressive Microenvironment: Tumors can create a local environment that suppresses immune responses, involving regulatory T cells (Tregs) and myeloid- derived suppressor cells (MDSCs). Antigen Loss Variants: Tumors may lose or alter the expression of antigens, making them less recognizable to the immune system Overall, the interplay between the immune system and cancer is a dynamic and evolving field, with significant implications for the diagnosis, treatment, and prognosis of cancer patients.
- 6. 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:
- 7. a)Hypercalcemia Symptomatic hypercalcemiaunrelated 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.
- 8. ii) Neuromyopathic syndromes About5% 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.
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