29  Apheresis

Key Points
  • Apheresis: Selectively removes plasma/RBCs/WBCs/platelets; replaces w/ fluid or cellular therapy
  • ASFA guidelines: Categories I-II = strongest evidence; published every 3-4 years
  • TPE (plasma exchange): Vol 1-1.5 plasma vol; replace w/ 5% albumin, FFP, or NS
    • Indications (ASFA I): TTP, MG, GBS, hyperviscosity, thrombotic microangiopathy
  • RBC exchange: SCD acute chest, stroke (target HbS <30%); monitor FCR for adequacy
  • Leukapheresis: Hyperleukocytosis (AML WBC >100K w/ sx); weak evidence monotherapy
  • ECP: Dendritic cells via UV-A + 8-MOP; GVHD, cutaneous T-cell lymphoma
  • Mobilization: G-CSF (1st line) + plerixafor (poor mobilizers) + motixafortide (recent)
  • Access: Central line preferred (jugular/subclavian/femoral); flow 2-3 mL/min
  • Anticoagulation: Citrate (preferred) vs heparin; watch citrate hypocalcemia

29.1 Overview

Apheresis = selective removal/manipulation of blood component w/ replacement fluid or cellular therapy. Uses: plasma disorders, RBC abnormalities, WBC/platelet dyscrasia, hematopoietic/immune disorders.

29.2 Technical Considerations

29.2.1 Vascular Access & Anticoagulation

  • Central access preferred: Jugular, subclavian, femoral > peripheral
  • Flow rate: 2-3 mL/min maintains adequate access & treatment time
  • Anticoagulation:
    • Citrate (1st line): Binds ionized Ca²⁺; reduces HIT risk
    • Heparin: Risk of HIT; watch bleeding perioperatively
    • HIT history → citrate mandatory
  • Procedure intensity: ↑ removal = ↑ complications (hypotension, citrate hypocalcemia)
  • Adverse events: Hypotension, citrate-related hypocalcemia, vasovagal reactions; rare seizure w/ replacement

29.2.2 Red Cell Exchange (RCE)

Indications: SCD acute chest, stroke; maintains Hb/Hct, ↓ complications.

  • Target HbS fraction: <30% in acute crises
  • Frequency: Q4 weeks initially; longer intervals after stabilization
  • FCR (fractional cell retention): Post/pre RCE ratio; ensures adequate donor RBC removal & ↓ alloimmunization
  • Adverse events: Similar to TPE; transfusion risks w/ donor RBCs
  • Euvolemia: Maintained via balanced removal/replacement

29.2.3 Therapeutic Plasma Exchange (TPE)

Mechanism: Removes pathogenic plasma (antibodies, immune complexes, abnormal proteins).

  • Vol removed: 1-1.5 plasma volumes typical
  • Replacement fluids: 5% albumin, FFP, or NS (titrate to clinical response)
  • ASFA Category I indications:
    • TTP (thrombotic thrombocytopenic purpura)
    • MG (myasthenia gravis)
    • GBS (Guillain-Barré syndrome)
    • Hyperviscosity syndrome (>4% IgM macroglobulinemia)
  • Anticoagulation strategy:
    • Heparin: Factor Xa/IIa inhibition; ↑ bleeding risk
    • Citrate (HIT history): Preferred; watch Ca²⁺ levels
  • Diminishing returns: 1.5 PV removes ~2/3 original plasma; >1.5 → minimal benefit w/ ↑ alloimmunization risk

29.2.4 Extracorporeal Photochemotherapy (ECP)

Mechanism: PBMCs + 8-MOP (8-methoxypsoralen) + UV-A → dendritic cells (immunomodulation).

  • Process: Centrifugation, 8-MOP exposure, UV-A treatment, reinfusion
  • Indications: GVHD (chronic), cutaneous T-cell lymphoma
  • Schedule: Q2 weeks × 6-12 mo; adjust per response
  • Mechanism: DC-mediated antigen presentation → T-cell regulation
  • Evidence: FDA-approved; combine w/ other tx for optimal outcomes

29.3 Leukocytapheresis & Thrombocytapheresis

Goal: Cytoreduction in symptomatic hyperleukocytosis/thrombocytosis; prevents neurologic/pulmonary/renal complications.

  • Reduction rate: 50-60% per procedure
  • Hyperleukocytosis: AML WBC >100K w/ neuro/pulmonary sx
    • 1st line: Hydroxyurea + chemo (not apheresis alone)
    • Apheresis: Bridging in severe cases or pregnancy
  • Platelet transfusion:
    • Avoid if possible (paradoxical ↑ risk)
    • If indicated: Give only after cytoreduction; rule out alloimmunization

29.4 PBMC Collection & Mobilization

Purpose: Source material for autologous/allogeneic transplant, CAR-T, DLI.

29.4.1 Mobilization Agents

  • G-CSF (filgrastim): 5-10 μg/kg/day; standard 1st line for HPC mobilization
  • Plerixafor (AMD3100):
    • CXCR4 antagonist → ↑ CD34+ release from BM
    • Adjunct for poor mobilizers on G-CSF
    • Rapid onset (rapid & significant ↑ in circulating WBC)
  • Motixafortide: Dual CXCR4/CXCL12 antagonist; recent agent; optimizes CD34+ yield
Mobilization Agents
Agent Mechanism Dosing/Use
G-CSF ↑ Myeloid progenitor mobilization 5-10 μg/kg/day; 1st line
Plerixafor CXCR4 antagonist; ↑ CD34+ release Adjunct for poor mobilizers
Motixafortide Dual CXCR4/CXCL12 antagonist ↑ Yield; recent
Clinical Pearls
  • RCE targets: HbS <30% acute; monitor FCR; prevent alloimmunization w/ each exchange
  • TPE volume: 1-1.5 PV standard; calculate per weight/Hct; higher volumes minimal benefit
  • ECP: FDA-approved monotherapy; best w/ concurrent other tx; slow onset (weeks-months)
  • Hyperleukocytosis: Apheresis bridging only; chemo + hydroxyurea = definitive tx
  • Access: Central line mandatory for safety; avoid peripheral lines

29.5 Bibliography

Balduzzi A, Arpinati M. G-CSF in the mobilization of hematopoietic progenitors. In: Principles of Apheresis Technology. Internal Principles of Apheresis Medicine. 7th ed. American Society for Apheresis; 2020.

Connelly-Smith L, Alquist CR, Aqui NA, et al. Guidelines on the use of therapeutic apheresis in clinical practice—evidence-based approach from the writing committee of the American Society for Apheresis. J Clin Apher. 2023;38(2):77–278.

Raval JS, Racadio NE, Pagleeroni J, et al. Reduced indications for rapid red cell exchange. Br J Haematol. 2014;164(3):342–351.

Spath KJ, Lin YW, Davis JM, et al. Plasma exchange in therapy. Transfusion. 2016;56(10):2825–2836.

Schwartz J, Winters JL, Padmanabhan A, et al. Guidelines on the use of therapeutic apheresis in clinical practice—evidence-based approach. J Clin Apher. 2013;28(3):145–284.