Dialyzable leukocyte extract

Summary

Dialyzable leukocyte extract (DLE), also known as transfer factor, is a biological immunomodulator prepared from disrupted mammalian (typically bovine or human) leukocytes via dialysis. It is approved in some countries (notably Mexico and several Eastern European nations) for adjunctive treatment of immunodeficiency states, recurrent infections, viral diseases, and certain cancers. It remains investigational or unregistered in the US and most Western markets.

Mechanism of Action

Dialyzable leukocyte extract (DLE) contains a heterogeneous mixture of low-molecular-weight peptides and polynucleotides derived from disrupted leukocytes. It transfers cell-mediated immunity by modulating T-lymphocyte activity, enhancing natural killer cell function, promoting cytokine production (including interferon-gamma and interleukin-2), and augmenting antigen-specific and non-specific immune responses.

Routes of Administration

Goals & Uses

• Adjunctive cancer immunotherapyOncologyLow
• Adjunctive therapy in tuberculosisInfectious DiseaseLow
• Recurrent respiratory tract infectionsImmunomodulation / Infection PreventionModerate
• Atopic dermatitis / allergic conditionsDermatology / AllergyLow
• Adjunctive therapy in primary immunodeficiencyImmunodeficiencyModerate
• Adjunctive treatment in herpetic infectionsAntiviral / ImmunomodulationModerate

Contraindications

• Autoimmune diseasesImmunologicalHigh
• PregnancyPopulationModeratePotential fetal risk or insufficient safety data
• Organ transplant recipients on immunosuppressionTransplantHigh
• Known hypersensitivity to DLE or bovine proteinsAllergyHigh

Adverse Effects

• Allergic reactionsImmunologicalRare
• Autoimmune exacerbationImmunologicalRare
• Injection site reactionsLocalCommon
• Gastrointestinal discomfortGastrointestinalUncommon
• Fever / flu-like symptomsSystemicUncommon

Drug Interactions

• Biologic immunomodulators (TNF inhibitors, anti-IL agents)Moderate
• Live vaccinesLow
• Immunosuppressants (corticosteroids, cyclosporine, tacrolimus)Moderate

Population Constraints

• Pediatric patientsAgeRelative
• Pregnant or lactating womenReproductiveRelative
• Elderly patientsAgeRelative
• Patients with active autoimmune diseaseImmunologicalRelative

Regulatory Status

• European UnionUnknownApproved in some Eastern European countries (e.g., Czech Republic as Immodin); not centrally approved by EMA. Status varies by member state.
• United StatesUnapprovedNot FDA-approved as a drug. Bovine transfer factor sold as dietary supplement but not recognized as a pharmaceutical. Research use only in clinical settings.
• United KingdomUnknownNot approved by MHRA as a licensed medicine. No current marketing authorization in the UK.

Approved and marketed in Mexico (as Transferon) for recurrent respiratory infections and as an immunomodulator. Approved in Cuba and some Eastern European countries. Not approved by the FDA in the US; classified as a research/investigational agent in the US and EU. OTC transfer factor supplements (typically bovine-derived) are sold in the US but are not FDA-approved drugs.

Evidence & Sources

No sources recorded yet.