ImmunologyLesson 3 of 4 in the course Adaptive Specific Host Defenses

T-Cell Development, Diversity, Subsets, and Effector Functions

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson introduces cellular immunity and follows T lymphocytes from their origins in bone marrow through maturation in the thymus. It also explains how selection and tolerance help prevent harmful immune reactions against the body’s own tissues.

Humoral immunity uses antibodies to target pathogens and toxins, especially while they are in extracellular spaces. Once a pathogen enters a host cell, antibodies generally cannot reach it. Cellular immunity addresses this challenge: T lymphocytes recognize and help eliminate infected cells and coordinate other immune defenses.

All flashcards

What is central tolerance?
Thymic safeguards that reduce the number of self-reactive T cells released into the body.
How does a T-cell receptor recognize an antigen?
It binds a specific epitope presented in association with an MHC molecule.
What is a major function of TH2 cells?
They support B-cell activation and help direct antibody class switching.
How do cytotoxic T cells induce death in infected target cells?
They release perforin and granzymes, which trigger apoptosis in the target.
How can a superantigen trigger widespread T-cell activation?
It bridges MHC II and the TCR beta-chain variable region outside the antigen-binding cleft.

Quiz questions

  1. During helper T-cell activation, what role does CD4 play?Answer: It binds a separate region of MHC II and helps stabilize the interaction.
  2. Which response is associated with TH2 cells?Answer: Supporting B-cell activation and antibody class switching.
  3. How do cytotoxic T cells identify infected host cells?Answer: They recognize pathogen-derived epitopes presented with MHC I.
  4. What is a typical role of memory helper T cells?Answer: They help produce a faster, stronger response after re-exposure to the same antigen.
  5. How do superantigens bypass normal T-cell antigen specificity?Answer: They bridge MHC II and the TCR beta-chain variable region outside the antigen-binding cleft.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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