13. Antitumor Immunity and Immunodeficiencies

Question 1

What mechanism eliminate tumor cells in healthy subjects?

Answer 1

Anti-tumor control mechanism

Question 2

How can tumor cells escape control?

Answer 2

• Fast proliferation, mutations, high diversoty

Question 3

What are oncogens?

Answer 3

• Gene coding proteins which can induce malignant transformation
• Viral/ v-onc
• Exons

Question 4

What are proto-oncogens?

Answer 4

• Are present and function in physiologically intact cells -> can become oncogenes when mutated
• Cellular/ c-onc
• Exons or introns

Question 5

Main function of oncogens?

Answer 5

To modulate proliferation or apoptosis

Question 6

Tumor antigens only expressed by tumor cells

Answer 6

Tumor specific antigens (TSA)

Question 7

Tumor antigens expressed by tumor cells + some normal cells

Answer 7

Tumor associated antigens (TAA)

Question 8

Oncofetal oncogens

Answer 8

• TAAs
• Normally expressed during a specific phase of embryogenesis
• Not immunogenic

Question 9

Significance of oncofetal oncogens

Answer 9

• They are diagnostic and prognostic markers

- Serum cc. correlates with tumor mass, level of differentiation and response to therapy

Question 10

Carcinoembryonic antigen (CEA)

Answer 10

• Discovered in extracts of adenocarcinoma of colon

- Heterogenous glycoproteins

Question 11

Alpha-fetoprotein (AFP) increased in what conditions?

Answer 11

• Hepatocellular cc
• Malignant teratoma
• Serum level inc. in metastatic tumors in liver + acute hepatitis

Question 12

Carcinoembryonic antigen (CEA) elevated in what conditions?

Answer 12

• GI, breast, pancreas, lung tumors
• Alcoholic cirrhosis
• Inflammations

Question 13

Only tumor cells w/o MHC can be lysed, why?

Answer 13

• Ly49 receptor recognizes MHC I and blocks NK cell activity

Question 14

Effects of NK cell on target cell

Answer 14

• NK cell has KIR (killer inhibitory receptor) that can bind MHC I on its surface, as well as KAR (killer activator receptor).
• If both KIR and KAR binds, MHC I is present and theres no apoptosis
• Only KAR bound to target cell -> apoptosis

Question 15

Deficiency causing SCID

Answer 15

• Lack of T lymphocytes and adaptive immunity causes severe combined immunodeficiency disease

Question 16

Cause of DiGeorge syndrome

Answer 16

22q11.2 deletion syndrome

Question 17

Cause of XLA

Answer 17

• X-chromosome linked agammaglobulinemia

- Deficiency of B cells and IgG in peripheral blood

Question 18

Hyper-IgM syndrome

Answer 18

Patients unable to transform IgM to IgG, A and E because they lack T cell CD40L

Question 19

Selective IgA deficiency

Answer 19

• SIGAD

- Deficiency of serum IgA because of a problem with the terminal differentiation of B cells

Question 20

Chronic granulomatosis (CGD)

Answer 20

• Dec. number and impaired function of phagocytes because of NADH/NADPH oxidase def. in neutrophils

Question 21

Deficiency of classical pathway components (C1-3) leads to

Answer 21

Immune-complex disease

Question 22

Deficiency of MBL pathway components (MBL, MASP1+2, C2, C4) leads to

Answer 22

Deficiency of MBL leads to bacterial infections, mainly in childhood

Question 23

Deficiency of alternative pathway components (Factor D + P) leads to

Answer 23

Infections with pyogenic bacteria and Neisseria spp. but no immunecomplex disease

Question 24

Deficiency of C3 leads to

Answer 24

Infection with pyogenic bacteria and Neisseria spp. + sometimes immune-complex disease

Question 25

Deficiency of MAC components (C5-9) leads to

Answer 25

Infection with Neisseria spp.

Question 26

Symptoms of Wiskott-Aldrich syndrome (WAS)

Answer 26

Eczema, thrombocytopenia, immune def., melena

Question 27

Genes delaying progression from HIV to AIDS

Answer 27

CCR5, CCR2, CXCL12