13 antigen signalling in B cell lymphoma Flashcards

1
Q

Why do many B-cell neoplasms retain surface BCR expression despite IG-associated translocations?

A

Ongoing antigen selection for functional BCR
SHM profiles show non-random mutations, suggesting selection pressure

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2
Q

What is the significance of IG sequence heterogeneity in B-cell lymphomas?

A

Indicates ongoing somatic hypermutation (SHM) and antigen-mediated selection.

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3
Q

How does SHM suggest selection for functional antigen receptors?

A

CDR regions have a high concentration of mutations
FR regions have fewer mutations → preserving BCR function

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4
Q

Which B-cell neoplasms express stereotyped BCRs?

A

Chronic Lymphocytic Leukaemia (CLL)
Mantle Cell Lymphoma (MCL)

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5
Q

What are stereotyped BCRs?

A

BCRs with highly homologous sequences, including:

Same V/D/J segment usage
Similar CDR3 sequences
Identical heavy-light chain pairings

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6
Q

What percentage of CLL cases carry just 19 different CDR3 sequences?

A

12% – an extremely non-random distribution.

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7
Q

What does stereotyped BCR usage in lymphomas suggest?

A

Recognition of common antigens driving B-cell expansion.

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8
Q

Which B-cell lymphomas express BCRs that recognise autoantigens?

A

Subset of CLL
Subset of MCL (LRPAP1)
Subset of MALT lymphoma (Sjogren’s syndrome)
Subsets of DLBCL (SAMD14, ARS2)

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9
Q

Which B-cell neoplasms recognise foreign pathogenic antigens?

A

NLPHL (M. catarrhalis)
MALT lymphoma (e.g., Helicobacter pylori)

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10
Q

What is MALT lymphoma?

A

An indolent lymphoma arising from chronic inflammation or infection.

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11
Q

Which infections are linked to MALT lymphoma?

A

Helicobacter pylori (stomach)
Borrelia burgdorferi (skin)
Chlamydia psittaci (orbit)

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12
Q

Which autoimmune diseases are associated with MALT lymphoma?

A

Sjogren’s syndrome (salivary glands)
Autoimmune thyroiditis (thyroid)

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13
Q

How can gastric MALT lymphoma be treated?

A

Antibiotic therapy to eradicate Helicobacter pylori.

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14
Q

What is the role of BCR signalling in B-cell lymphomas?

A

Drives proliferation and survival
Some lymphomas require chronic antigen stimulation

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15
Q

What is Lyn, and what is its role in BCR signalling?

A

Lyn is a kinase that provides negative feedback to regulate BCR signalling.

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16
Q

What is chronic active BCR signalling?

A

A condition where BCR signalling remains constitutively active, even without antigen binding.

17
Q

Which lymphoma subtype relies on chronic active BCR signalling?

A

ABC-DLBCL (Activated B-Cell Diffuse Large B-Cell Lymphoma).

18
Q

Which genetic alterations affect BCR signalling in DLBCL?

A

Mutations in CARD11 → NF-κB activation
Mutations in BTK → Constitutive signalling
Mutations in CD79A/B → Hyperactive BCR

19
Q

What are the key principles of B-cell neoplasia related to BCR signalling?

A

Many B-cell lymphomas retain normal B-cell properties
Antigen receptor signalling is essential for survival in some lymphomas

20
Q

Why is BCR signalling a therapeutic target in B-cell lymphomas?

A

Many lymphomas depend on BCR activation
Blocking key signalling molecules can disrupt tumour survival

21
Q

Which inhibitors target BCR signalling in B-cell lymphomas?

A

BTK inhibitors
NF-κB inhibitors
BCL2 inhibitors
SYK inhibitors
PI3K inhibitors

22
Q

What is a major BTK inhibitor used in lymphoma treatment?

A

Ibrutinib (a Bruton’s tyrosine kinase (BTK) inhibitor).

23
Q

How does ibrutinib work?

A

Blocks BTK-dependent BCR signalling, reducing tumour survival.

24
Q

What is a major PI3K inhibitor used in lymphoma treatment?

A

Idelalisib, which blocks PI3K-dependent survival pathways.

25
Q

How does precision medicine improve DLBCL treatment?

A

Uses molecular profiling to predict:

Lymphoma subtype
Best targeted therapy

26
Q

What is the key principle of precision medicine in B-cell lymphoma?

A

Understanding the molecular basis of lymphoma leads to new targeted treatments.