immunohistochemistry Flashcards

1
Q

What is immunohistochemistry routinely used for?

A

Identification of specific or highly selective cellular epitopes or antigens in frozen or paraffin-embedded tissues.

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2
Q

What does immunocytochemistry detect?

A

Organism in cytologic preparations (fluids, sputum samples, and fine needle aspirates).

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3
Q

What is the principle of immunohistochemistry and immunocytochemistry?

A

Antigen-antibody interactions.

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4
Q

What are the applications of immunohistochemistry?

A

Disease diagnosis, drug development, biological research.

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5
Q

What are polyclonal antibodies?

A

Antibodies produced by several clones of plasma cells using laboratory animals such as rabbits, goats, pigs, sheep, horses, guinea pigs.

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6
Q

How are polyclonal antibodies produced?

A

Lab animals are immunized with a purified specific immunogen having the antigen of interest, which responds by producing humoral antibodies against the antigen. Immunoglobulin-rich serum is collected from the lab animal.

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7
Q

What are monoclonal antibodies?

A

Antibodies produced by a single clone of plasma cells using hybridoma and cloning techniques, typically involving mice.

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8
Q

What is proteolytic enzyme digestion used for in sample preparation?

A

To break down formalin cross-links to unmask and allow certain antigenic sites to be exposed, useful for heavy chain immunoglobulins, complement, and specific antigens.

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9
Q

What enzymes are commonly used in proteolytic enzyme digestion?

A

Trypsin (0.1% trypsin in 0.1% CaCl) and protease (0.05 to 0.1% protease) adjusted to pH 7.8 with NaOH and preheated to 37°C.

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10
Q

What is microwave antigen retrieval?

A

Boiling formalin-fixed deparaffinized sections in buffers such as 0.01 M citrate buffer (pH 6.0), EDTA (pH 8.0), Tris EDTA (pH 8 or 10.0) with optimal exposure to heat for 10 to 60 minutes, most satisfactory at 20 minutes.

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11
Q

What is pressure cooker antigen retrieval?

A

A less time-consuming method with more consistent antigen recovery.

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12
Q

What is keratin a marker for?

A

Epithelial cells, including epithelial tumors (carcinomas) and non-epithelial tumors (mesotheliomas and non-seminomatous germ cell tumors).

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13
Q

What carcinomas are positive for CK7?

A

Lung, breast, uterus, and ovaries carcinomas.

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14
Q

What carcinomas are positive for CK20?

A

Colon and stomach carcinomas.

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15
Q

What is epithelial membrane antigen (EMA)?

A

A high molecular weight protein aiding in determining the site of the tumor, positive in adenocarcinomas of the breast, lung, and kidneys.

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16
Q

What is carcinoembryonic antigen (CEA)?

A

An oncofetal antigen present in GIT, pancreas, lung, breast, ovary, uterus, and cervix carcinomas, differentiates adenocarcinoma from mesothelioma.

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17
Q

What is thyroid transcription factor-1 (TTF-1)?

A

Distinguishes lung adenocarcinoma from mesothelioma, positive in thyroid, lung, and neuroendocrine tumors.

18
Q

What is prostate-specific antigen (PSA)?

A

Extremely useful in the diagnosis of prostatic adenocarcinoma, positive in certain pancreatic and salivary gland tumors.

19
Q

What is actin a marker for?

A

Muscle differentiation, identifying tumors derived from smooth, skeletal, and cardiac muscle.

20
Q

What is vimentin a marker for?

A

A 57 kD intermediate filament in normal mesenchymal cells and their neoplastic counterparts, always positive in melanomas and Schwanommas.

21
Q

What is desmin a marker for?

A

A 53 kD intermediate filament in smooth and striated muscles, highly specific for myogenic tumors.

22
Q

What is GFAP (glial fibrillary acidic protein)?

A

A 51 kD intermediate filament protein expressed by CNS glial cells, particularly astrocytes, used to confirm astrocytoma diagnosis.

23
Q

What is neurofilament (NF)?

A

Expressed by cells of neural origin, particularly neurons, peripheral nerves, and neuroendocrine cells, positive in tumors with neuronal or neuroendocrine differentiation.

24
Q

What is S-100 protein?

A

A low molecular weight calcium-binding protein expressed by CNS glial cells, Schwann cells, melanocytes, and other cell types.

25
Q

What is neuron-specific enolase (NSE)?

A

An isoenzyme marker providing strong evidence of neural or neuroendocrine differentiation.

26
Q

What is chromogranin?

A

Found in neural secretory granules of endocrine tissues, a marker for neuroendocrine differentiation.

27
Q

What is synaptophysin?

A

A 38 kD transmembrane protein associated with presynaptic vesicles of neurons, identified in normal neurons and neuroendocrine cells.

28
Q

What is human chorionic gonadotropin (HCG)?

A

Synthesized by placental syncytiotrophoblasts, a marker for choriocarcinoma.

29
Q

What is alpha fetoprotein (AFP)?

A

Synthesized by normal hepatocytes, a marker for endodermal sinus tumors and hepatocellular carcinomas.

30
Q

What is placenta-like alkaline phosphatase (PLAP)?

A

Produced by placental syncytiotrophoblasts in late pregnancy, a marker for germ cell tumors.

31
Q

What markers are positive for myogenic tumors?

A

Actin, desmin, myo-D1, myoglobin, myogenin.

32
Q

What markers are positive for fibrohistiocytic tumors?

A

CD68 or FAM 56 with alpha-1-antitrypsin and alpha-1-antichymotrypsin for malignant, vimentin for undifferentiated.

33
Q

What markers are positive for vascular tumors?

A

Factor VII-related antigen, CD31, Ulex europaeus 1.

34
Q

What markers are positive for melanomas?

A

S100 protein, melanosome (HMB-45), Melan-A (MART-1).

35
Q

What markers are positive for lymphomas?

A

Leukocyte common antigen (LCA), CD3, CD4, CD5 for T cells, CD19, CD20, CD23 for B cells, CD15, CD30, Ig LC, and HC for Reed-Sternberg cells.

36
Q

What are cell proliferation markers?

A

Ki-67 (MIB-1), PCNA (proliferating cell nuclear antigen).

37
Q

What are the types of labels used in immunohistochemistry?

A

Enzyme labels, colloidal metal labels, fluorescent labels, radiolabels.

38
Q

What is the traditional direct technique?

A

The primary antibody is conjugated directly to the label, with direct interaction between the labeled antibody and antigen in the histological or cytological preparation.

39
Q

What is the two-step indirect technique?

A

An unconjugated primary antibody binds to the antigen, followed by a labeled-secondary antibody directed against the primary antibody.

40
Q

What is the three-step indirect technique?

A

Another labeled-antibody is used directed against the labeled-secondary antibody.