Host immune response and paraneoplastic syndrome

Pathology

1. PRESENTED BY:
SALAJ SONKAR(93)

2. NEOPLASM : A neoplasm, 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 RESPONSE MECHANISM
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 EVASION STRATEGY
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 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.

8. 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.

9. SUMMARY OF PNS