Blood Banking - Lecture - 13 - Autoimmune Hemolytic Anemia - Part 2 - Complete

Drug binds to RBC

Drug-induced IHA - Drug adsorption

Mechanism

IgG

Drug-induced IHA - Drug adsorption

Detected by DAT

Reactive w/ drug cells

Drug-induced IHA - Drug adsorption

Eluate reaction

Extravascular

Drug-induced IHA - Drug adsorption

Type of hemolysis

Complement binds to RBCs

Drug-induced IHA - Immune complex

Mechanism

Complement C3

Drug-induced IHA - Immune complex

Detected by DAT

Nonreactive

Drug-induced IHA - Immune complex

Eluate reaction

Intravascular

Drug-induced IHA - Immune complex

Type of hemolysis

True autoantibody

Drug-induced IHA - Autoantibody

Mechanism

IgG

Drug-induced IHA - Autoantibody

Detected by DAT

Pan-reactive

Drug-induced IHA - Autoantibody

Eluate reaction

Extravascular

Drug-induced IHA - Autoantibody

Type of hemolysis

Adsorption

Drug-induced IHA cause

About IgG and drug-coated cells

Immune complex

Drug-induced IHA cause

About complement and intravascular innocent bystander damage

Autoantibody

Drug-induced IHA cause

Autoantibody induction, like what you see in Aldomet or Methyldopa, looks exactly like warm autoimmune hemolytic anemia.

Warm AIHA

Immune hemolytic anemia

Most common (70%); mediated by IgG; causes extravascular hemolysis in the spleen

Cold AIHA

Immune hemolytic anemia

Triggered by cold temperatures: mediated by IgM and Complement; causes acrocyanosis

Paroxysmal cold hemoglobinuria

Immune hemolytic anemia

Biphasic IgG (Donath-Landsteiner); binds in the cold and lyses cells at 37C

Drug-induced IHA

Immune hemolytic anemia

Triggered by medications; varies from "innocent bystander" lysis to true autoantibody production.

37°C

Warm AIHA - Diagnostic findings

Optimal temperature

IgG and/or C3

Warm AIHA - Diagnostic findings

DAT results

IgG

Warm AIHA - Diagnostic findings

Antibody class

Spherocytes

Warm AIHA - Diagnostic findings

Blood smear

4-30°C

Cold AIHA (CHD) - Diagnostic findings

Optimal temperature

C3 only

Cold AIHA (CHD) - Diagnostic findings

DAT results

IgM

Cold AIHA (CHD) - Diagnostic findings

Antibody class

Agglutination

Cold AIHA (CHD) - Diagnostic findings

Blood smear

4°C

Cold AIHA (CHD) - Diagnostic findings

Temperature it binds

37°C

Cold AIHA (CHD) - Diagnostic findings

Temperature it lyses

C3 only

Cold AIHA (CHD) - Diagnostic findings

DAT results

IgG

Cold AIHA (CHD) - Diagnostic findings

Antibody class

Polychromasia

Cold AIHA (CHD) - Diagnostic findings

Blood smear

Paroxysmal cold hemoglobinuria

IHA where an IgG antibody that acts like a cold one.

Direct Antiglobulin Test

Primary screening tool. It tells you if sensitization is happening in vivo.

It answers: Is there something coating the patient's cells right now?

EDTA

Anticoagulant used for DAT to avoid the "in vitro" complement binding seen in clotted samples.

High Reticulocyte count, Indirect bilirubin, LDH, Low Haptoglobin

If 3+ DAT w/ pan-reactive eluate, what are the laboratory markers of hemolysis?

Benign antibodies

If the lab results say "Hemolysis" but the patient's Hemoglobin is stable, and they look fine, re-evaluate your technique or look for:

To ensure that autoantibodies do not mask a potentially fatal alloantibody

Primary goal in Blood bank

Pre-warming

Specialized technique for cold agglutinin interference

Adsorptions

Specialized technique to unmask alloantibodies

Elutions

Specialized technique to identify what is coating the cells

Donath-Landsteiner test

Specialized technique for suspected PCH

Dithiothreitol

Reagent that breaks IgM disulfide bonds. Useful for resolving cold agglutinin discrepancies.