CPR APPLICATIONS FOUNDATION · CHAPTER 3 · ABNORMAL
Abnormal Foundations of Immunology
Use a chapter-level CPR map to organize the recurring ways normal function breaks and how those deviations present.
Supplemental foundation map: this page orients the detailed CPR Applications for Chapter 3. It is not part of the canonical CPR object inventory.
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Normal Foundations
Abnormal Foundations · You are here
Treatment Foundations
3.10 · SOURCE CPR FOUNDATION
Concept
Abnormal immunology is misdirected, excessive, or absent immune function. Most abnormal immune vignettes fall into hypersensitivity, autoimmunity, or immunodeficiency. Timing helps separate immediate IgE reactions from delayed T-cell reactions. Organ involvement, complement levels, cytopenias, eosinophilia, and the infection pattern reveal the mechanism.
Pattern
Step 1 usually asks which immune mechanism is dominant before asking for the disease label. The key is to identify the target, timing, immune cell or antibody involved, and tissue pattern.
Rule
- Label the immune mechanism first: decide whether the pattern is IgE mast-cell activation, IgG/IgM tissue injury, immune complex deposition, T-cell delayed injury, or immune deficiency.
- Use timing and distribution to classify injury: immediate allergic symptoms, targeted cytopenias, systemic deposition organs, and delayed skin reactions point to different mechanisms.
- Predict labs and complications from the mechanism: eosinophilia, low complement, cytopenias, granulomas, or opportunistic infections should follow logically.
Applications
- Rapid wheeze, urticaria, or hypotension after allergen exposure → consider IgE-mediated Type I hypersensitivity; timing alone is insufficient
- Targeted cytopenia → Type II hypersensitivity
- Nephritis rash arthritis → Type III hypersensitivity
- Delayed rash → Type IV hypersensitivity
- Recurrent opportunistic infections → immunodeficiency
CPR APPLICATIONS · ACTIVE REASONING
Classify hypersensitivity
Choose the best explanation before opening feedback. These unscored self-checks do not save responses.
Decision 1: Minutes after an allergen exposure, wheezing, urticaria and hypotension occur.
Mast-cell mediator release
Best explanation. Rapid airway, cutaneous and circulatory manifestations fit anaphylaxis; IgE is common but is not the only mechanism.
Soluble immune complexes
Why this is less appropriate: Type III immune-complex deposition usually produces a different pattern.
Decision 2: An IgG antibody binds a red blood cell surface antigen and triggers hemolysis.
Type II antibody-mediated injury
Best explanation. Type II injury involves antibody directed against cell-surface or matrix targets.
Type III immune complexes
Why this is less appropriate: Type III involves soluble antigen-antibody complexes depositing in tissues.
Decision 3: Days after exposure to a foreign protein, fever, rash, joint pains and low complement occur.
Type III immune-complex injury
Best explanation. Systemic inflammation and complement consumption can follow immune-complex deposition.
Type IV contact hypersensitivity
Why this is less appropriate: Type IV is a T-cell-mediated mechanism; the multisystem complement-consuming presentation favors Type III.
Transfer to a new scenario
Change one clinical finding, immune deficiency, microbial strategy or treatment context. Explain which mechanism changes and why; compare your reasoning against the explanations above.
Educational practice only; not individualized clinical guidance.
How to use this foundation map
- Read the Concept and identify the organizing mechanism.
- Use the Pattern to recognize how the mechanism tends to appear in Step 1-style reasoning.
- Restate the Rule without looking, then test whether each application follows from it.
- Move to the adjacent foundation layer or use question practice to test transfer.
When applying the organized knowledge to a case or question, pair CPR with the 5P Approach™.
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