Immunology lab

LKM

Liver Kidney Microsomal Antibodies

Primary disease associated with Anti-LKM-1

Autoimmune Hepatitis Type 2 (AIH-2)

Main target antigen of Anti-LKM-1

CYP2D6 enzyme

SMA

Smooth Muscle Antibodies

Which disease is associated with SMA

Autoimmune Hepatitis Type 1 (AIH-1)

Primary target structure of Smooth Muscle Antibodies (SMA)

Smooth muscle components, especially F-actin

AMA

Anti-Mitochondrial Antibodies

Which disease is associated with AMA

Primary Biliary Cholangitis (PBC)

AMA-M2

A specific subtype of anti-mitochondrial antibodies that targets PDC-E2 and strongly supports PBC diagnosis

Difference between AMA and AMA-M2

AMA detects a broader group of mitochondrial antibodies, whereas AMA-M2 specifically targets PDC-E2 and offers greater specificity for PBC

PCA

Parietal Cell Antibodies

Which diseases is associated with PCA

Autoimmune gastritis and Pernicious anemia

Target antigen of Parietal Cell Antibodies (PCA)

H/K -ATPase in gastric parietal cells

Target antigen of Anti-GBM antibodies

Glomerular basement membrane, primarily targeting type IV collagen

Disease associated with Anti-GBM antibodies

Anti-GBM Disease (Goodpasture Disease)

Autoimmune Hepatitis (AIH)

An autoimmune disorder in which the immune system targets and damages hepatocytes (liver cells)

Serologic distinction between AIH Type 1 and Type 2

Type 1 is characterized by ANA and SMA; Type 2 is characterized by Anti-LKM-1 and Anti-LC1

Primary Biliary Cholangitis (PBC)

A chronic autoimmune disease that damages small bile ducts in the liver, causing cholestasis.

Liver enzymes characteristically elevated in Primary Biliary Cholangitis (PBC)

ALP and GGT

Autoimmune Gastritis

Autoimmune destruction of gastric parietal cells, reducing hydrochloric acid and intrinsic factor secretion.

Pernicious Anemia

A form of anemia caused by vitamin B12 malabsorption due to a deficiency in intrinsic factor

Anti-GBM Disease

An autoimmune disease in which antibodies attack the basement membranes of the kidneys and lungs.

ANCA

Anti-Neutrophil Cytoplasmic Antibodies

Method commonly used to detect ANCA patterns

Indirect Immunofluorescence Assay (IFA)

Three main ANCA patterns identified by IFA

C-ANCA, P-ANCA, and atypical ANCA (A-ANCA / X-ANCA)

IFA staining pattern of C-ANCA

Diffuse granular staining throughout the cytoplasm

Primary target antibody associated with C-ANCA

Anti-Proteinase-3 (Anti-PR3)

Primary disease associated with C-ANCA and Anti-PR3

Granulomatosis with Polyangiitis (GPA)

Reason Anti-PR3 produces a C-ANCA pattern

Proteinase-3 remains distributed throughout the cytoplasm without migrating during ethanol fixation

IFA staining pattern of P-ANCA

Perinuclear staining around the nucleus

Primary target antibody associated with P-ANCA

Anti-Myeloperoxidase (Anti-MPO)

Diseases commonly associated with P-ANCA and Anti-MPO

Microscopic Polyangiitis (MPA) and Eosinophilic Granulomatosis with Polyangiitis (EGPA)

Mechanism causing P-ANCA pattern in ethanol fixation

Ethanol permeabilizes membranes and allows cationic MPO to migrate and bind to the negatively charged nucleus

Purpose of ethanol-fixed neutrophils in ANCA testing

To differentiate between C-ANCA and P-ANCA staining patterns

Purpose of formalin-fixed neutrophils in ANCA testing

To confirm whether a P-ANCA pattern is truly caused by Anti-MPO antibodies

Effect of formalin fixation on true Anti-MPO staining

Prevents MPO migration to the nucleus, causing the staining pattern to switch from perinuclear to cytoplasmic

Alternative designations for atypical ANCA

A-ANCA or X-ANCA

TPHA

Treponema pallidum Hemagglutination Assay

Test cells in TPHA

Red blood cells coated with Treponema pallidum antigens

Control cells in TPHA

Uncoated red blood cells lacking Treponema pallidum antigens

Target detected by TPHA test cells

Anti-Treponema pallidum antibodies in the patient's serum

Purpose of control cells in TPHA

To detect and rule out non-specific agglutination

Expected test and control cell results for a positive TPHA

Agglutination in test cells and no agglutination in control cells

Interpretation of agglutination observed in TPHA control cells

Non-specific agglutination has occurred, rendering the test result invalid and unreliable