MHC Overview and Practical Applications

Lecture Study Notes

Grading Approach

• Key Concepts

  • Grading based on a key created by the instructor.
  • Answers from students are reviewed to assess knowledge comprehension.
  • If only a few students answer a question correctly, it may indicate a need for less emphasis on that topic in grading.

• Point Structure

  • Decisions on point allocation depend on the number of students who have common answers.

Review Process

• Initial Feedback
  • General comments provided for early reviews, focusing on improvement areas (e.g., “More of this, less of that”).
  • Refinement of feedback in subsequent rounds leading to a final working document.
• Student Understanding
  • May include grading on students’ oral presentations of material to assess their understanding in depth.

Housekeeping Items

• Undergrad Interaction

  • Importance of a structured schedule for undergrad involvement.
  • Coordination with undergrads about sample handling and experimentation.

• Sample Management

  • Discusses extraction and testing of liver samples. Evaluating the practicality of running tests on those samples.
  • Importance of scheduling for sample collection in line with hormonal cycles.

MHC (Major Histocompatibility Complex) Overview

• Definition and Importance

  • MHC necessary for the immune system to process and recognize antigens, leading to adaptive immune responses.
  • Essential for presenting processed antigens to T cells (adaptive immune cells).

• MHC Terminology

  • MHC molecules (or proteins) are presented on cell surfaces, important for signaling adaptive immunity.
  • Terms such as 'MHC region' refers to the chromosome neighborhood coding for MHC proteins.

• Species-Specific Naming

  • Cattle's unica (BOLA) refers to bovine leukocyte antigens (a type of MHC).
  • Goats and sheep have different names based on classification, influenced by their respective scientific nomenclatures.

Chromosomal Structure of MHC

• MHC Region vs. MHC Molecule

  • MHC region as a neighborhood; MHC molecules as specific proteins that present antigens.
  • The existence of multiple MHC molecules coded within a specific MHC region.

• Diagram Analysis

  • Chromosome 23 and its regions for MHC class I (BOLA class I) and other MHC classes.
  • Difference between class I, II, and III MHC proteins and their functions.

Class I MHC Molecules

• Structure

  • A heterodimer containing an alpha heavy chain and a beta-2 microglobulin (not coded within the MHC region).
  • Functions in presenting antigens to CD8+ T cells.

• Genetic Diversity

  • The genetic variability found within bovine populations influences MHC functionality relating to disease resistance.

Class II MHC Molecules

• Composition

  • Comprises two chains: an alpha and a beta chain, which are encoded by MHC class II genes.
  • Interacts specifically with CD4+ T cells.

• Functional Role

  • Used for presenting extracellular proteins broken down in endosomal compartments to T cells.

MHC Class III Molecules

• Overview and Function
  • Contains immune-related genes that facilitate immune system operations but are not true MHC molecules like classes I and II.
  • Includes various proteins involved in immune response but does not interact directly with T cell receptors.

Ruminants and Immune Response

• Gamma Delta T Cells

  • Ruminants express a higher proportion of these cells compared to humans and mice, having implications for antigen recognition and response.

• Application in Disease Recognition

  • The discussion on utilizing MHC in studying immune responses and disease susceptibility in cattle.

Conclusion and Next Steps

• Review and Questions

  • Importance of clarifying complex concepts for better understanding of MHC, T cell, and B cell biology.
  • Strategies involving the immunological aspects to be discussed in future sessions.

• Future Class Scheduling

  • Further discussions planned on how MHC class variations affect inflammation and immune responses in ruminants.