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Mechanism of Drug Action (Drugs) > Immunosuppression (Drugs) > Flashcards

Immunosuppression (Drugs) Flashcards

1
Q

What is the mechanism of action of corticosteroids in causing immunosuppression?

A
  1. Suppresses secretion of factors that drive proliferation and differentiation of TH cells (e.g. IL-2 which promotes differentiation of TH1 cells).
  2. Suppresses secretion of pro-inflammatory cytokines (e.g. IL-1).
  3. Promotes secretion of anti-inflammatory cytokines (e.g. IL-1ra)
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2
Q

What is the mechanism of cyclophosphamide in immunosuppression?

A
  • Pro-drug which is converted to active phosphoramide mustard by liver P450 enzymes.
  • Alkylation of DNA causing cross-links to be formed between DNA of the same and different strands.
  • This inhibits DNA transcription and replication.
  • Results in death of fast-dividing lymphocytes (B cells and T cells).
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3
Q

What are the side effects of cyclophosphamide?

A
  • Bone marrow depression
  • Bladder irritation (metabolite acrolein activates TRPA1 in bladder nociceptors)
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4
Q

What is the mechanism of action of ciclosporin A (CsA) in immunosuppression?

A

CsA binds to CpN to form CpN-CsA complex, which binds to and inhibits CaN, preventing it from dephosphorylating NF-AT.

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5
Q

What is the mechanism of action of tacrolimus in immunosuppression?

A

Binds to and forms complex with FKBP that inhibits CaN and prevents it from dephosphorylating NF-AT.

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6
Q

What is the mechanism of action of basiliximab in immunosuppression?

A

Binds to CD25α subunit of IL-2 receptor and acts as antagonist, preventing role of IL-2 in activation of T and B cells.

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7
Q

What is the mechanism of action of belatacept in immunosuppression?

A
  • Chimera of modified CTLA-4 and Fc domain of IgG1.
  • CTLA-4 domain binds to B7 on pAPCs with great affinity and prevents activation of T cells via co-stimulation.
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8
Q

What is the mechanism of action of sirolimus in immunosuppression?

A
  1. Binds to FKBP to form FKBP-sirolimus complex.
  2. The complex inhibits activity of mTOR in mTORC1, which is part of an important proliferation pathway.
  3. This causes inhibition of T cell proliferation and thus immune response.
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9
Q

What is the mechanism of action of azathioprine (AZA) in immunosuppression?

A
  1. Converted to 6-MP via non-enzymatic reduction process.
  2. 6-MP is converted by HPRT to TIMP.
  3. TIMP is convered to 2 substances both inhibiting DNA synthesis:
    - MeTIMP (by TPMT): Inhibition of purine synthesis
    - 6-TGN (IMPDH): Incorporated into nucleic acids (DNA and RNA) and inhibits protein synthesis and nucleotide synthesis (probably via disruption of mRNA)
  4. This inhibits T cells and B cells in particular who are unable to synthesise nucleotides from intermediates of nucleotide breakdown (salvage pathway) and need to synthesise them de novo
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10
Q

What is the mechanism of action of mycophenolic acid in immunosuppression?

A
  • Inhibition of IMPDH, an enzyme required for de novo guanosine synthesis.
  • Inhibits T cells and B cells in particular who are unable to synthesise nucleotides from intermediates of nucleotide breakdown (salvage pathway) and need to synthesise them de novo
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11
Q

What are the properties of muromonab-CD3?

A
  • Murine mAb
  • Targets CD3
  • Treatment of acute rejection
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12
Q

What is the mechanism of action of alemtuzumab?

A

Binds to CD52 and targets mature lymphocytes for destruction only.

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13
Q

What are the clinical uses of alemtuzumab?

A
  1. Chronic lymphocytic leukaemia
  2. T cell lymphoma
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14
Q

What is the mechanism of action of ofatumumab?

A

Binds to CD20 on B cells and targets them for destruction.

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15
Q

What are the clinical uses of ofatumumab?

A

Chronic lymphocytic leukaemia

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16
Q

What is the mechanism of action of catumaxomab?

A
  1. Fc region binds epithelial cells
  2. One Fab region binds CD3 on T cells
  3. One Fab region binds EpCAM on tumour cells
  4. Brings T cells and tumour cells into close association so that T cells more likely to produce immune response against tumour cells
17
Q

What is the mechanism of action of trastuzumab emtansine?

A
  1. Combination of trastuzumab (HER2 specific) and maytansine (antimicrotubule)
  2. Binding of trastuzumab to HER2 causes internalisation
  3. In endosome, trastuzumab is degraded and maytansine is released
  4. Maytansine binds to tubulin and prevents polymerisation, causing cytotoxicity

Mechanism of Drug Action (Drugs) (26 decks)

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