# Immune Pathology

> Immune pathology for FMGE Pathology, covering hypersensitivity types, autoimmune antibodies, vasculitis profiles, immunodeficiency and transplant rejection.

- Canonical URL: https://prepelephant.com/topics/fmge/pathology/immune-pathology
- Exam / course: FMGE · Subject: Pathology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Immune Pathology", PrepElephant, https://prepelephant.com/topics/fmge/pathology/immune-pathology

## Direct answer

Immune pathology spans hypersensitivity reactions, autoimmune disease, vasculitis, immunodeficiency and transplant rejection. The Gell and Coombs classification anchors it: type I IgE immediate allergy, type II antibody-mediated cytotoxicity, type III immune-complex disease and type IV delayed T-cell hypersensitivity. FMGE repeatedly pairs an antibody or histological pattern with a disease — anti-dsDNA with lupus nephritis, anti-centromere with CREST, c-ANCA with granulomatosis with polyangiitis — so markers matter as much as clinical pictures.

## What you must remember

- Hypersensitivity: type I — anaphylaxis, asthma, urticaria; type II — transfusion reactions, haemolytic disease of the newborn, Graves disease, Goodpasture syndrome; type III — serum sickness, lupus, post-streptococcal glomerulonephritis; type IV — tuberculin test, contact dermatitis, type 1 diabetes, graft rejection.
- SLE: young women with malar rash, arthritis and serositis; ANA sensitive, anti-dsDNA and anti-Smith specific; Libman-Sacks endocarditis and full-house glomerulonephritis; hydralazine and procainamide cause anti-histone-positive drug lupus.
- Rheumatoid arthritis: symmetric small-joint synovitis with pannus, anti-CCP more specific than rheumatoid factor, swan-neck deformity, subcutaneous nodules, Felty syndrome. Sjögren adds sicca with anti-Ro and anti-La.
- Systemic sclerosis: diffuse disease with anti-Scl-70; limited CREST (calcinosis, Raynaud, oesophageal dysmotility, sclerodactyly, telangiectasia) with anti-centromere.
- Vasculitis: giant cell arteritis after fifty with jaw claudication, high ESR and blindness risk needing urgent steroids; Takayasu (pulseless) in young women; polyarteritis nodosa with hepatitis B; IgA vasculitis with palpable purpura in children; c-ANCA (PR3) with granulomatosis with polyangiitis.
- Immunodeficiency: Bruton X-linked agammaglobulinaemia (boys after six months, absent tonsils and B cells); DiGeorge 22q11 with thymic aplasia and hypocalcaemia; severe combined immunodeficiency with early candidiasis and BCG dissemination; selective IgA deficiency, the commonest, causes anaphylactic transfusion reactions.
- Transplantation: hyperacute rejection in minutes from preformed antibody; acute rejection weeks to months, T-cell mediated; chronic rejection as graft arteriosclerosis; graft-versus-host disease affects skin, liver and gut after allogeneic marrow grafts.

## Common confusion

Serum sickness (type III) appears one to two weeks after exposure with fever, urticaria and arthralgia, unlike minutes-onset IgE anaphylaxis. Anti-dsDNA tracks lupus activity while anti-Smith stays stable; c-ANCA pairs with granulomatosis with polyangiitis and p-ANCA with the other small-vessel vasculitides. In rejection timing, remember antibody causes hyperacute and T cells cause acute rejection.

## Exam-focused takeaway

FMGE gives a vignette and expects one antibody or vasculitis name: malar rash with proteinuria (anti-dsDNA), temporal headache with visual loss (giant cell arteritis, steroids first), a boy with recurrent bacterial infections and absent immunoglobulins (Bruton). Hypersensitivity classification and rejection timing are near-guaranteed marks.

## Frequently asked questions

### Which antibody is most specific for SLE?
Anti-Smith; anti-dsDNA is also specific and correlates with nephritis and activity. ANA is the sensitive screen but not specific.

### What is CREST syndrome?
Limited systemic sclerosis — calcinosis, Raynaud, oesophageal dysmotility, sclerodactyly and telangiectasia — with anti-centromere antibody. Diffuse disease with anti-Scl-70 is more aggressive.

### How is graft rejection classified temporally?
Hyperacute within minutes to hours from preformed antibodies, acute within weeks to months from T cells, and chronic over months to years as vascular fibrosis. Each needs different prevention and treatment.

### Which immunodeficiency follows 22q11 deletion?
DiGeorge syndrome with thymic aplasia, T-cell deficiency, hypocalcaemia from parathyroid aplasia and conotruncal heart defects — summarised as CATCH-22.

### What type of hypersensitivity is the tuberculin reaction?
Type IV delayed hypersensitivity from sensitised CD4 cells recruiting macrophages, peaking at 48 to 72 hours; it underlies the Mantoux test.

### Which vasculitis causes absent upper-limb pulses?
Takayasu arteritis of the aortic arch and branches in young women; giant cell arteritis is its counterpart after age fifty with temporal headache and jaw claudication.