D2.191 - Autoimmune Disease Unmasked by Allergic Immunotherapy: A Case of Systemic Lupus Erythematosus (SLE) After SCIT
Case report
Background
Subcutaneous immunotherapy (SCIT) is widely used to enhance immune tolerance in allergic patients by promoting regulatory T-cell (Treg) expansion and shifting Th2-driven responses toward Th1 immunity. While generally safe, immune modulation could, in rare cases, contribute to autoimmune disease activation in genetically predisposed individuals. We present a case of systemic lupus erythematosus (SLE) unmasked after SCIT initiation, raising questions about potential screening and risk assessment strategies.
Case Presentation
A 30-year-old male with allergic rhinitis, no prior history of autoimmune disease, and no known family history of autoimmunity started SCIT for grass pollen allergy. He followed a standard up-dosing regimen over 12 weeks, transitioning to monthly maintenance injections. After six months, he developed progressive fatigue, polyarthritis, and photosensitive skin rashes. Laboratory tests revealed:
- Positive antinuclear antibodies (ANA, 1:1280, speckled pattern)
- Anti-double-stranded DNA (dsDNA) positivity
- Low complement levels (C3: 56 mg/dL, C4: 8 mg/dL)
A diagnosis of SLE was confirmed based on the 2019 EULAR/ACR classification criteria. SCIT was discontinued, and the patient was started on hydroxychloroquine and low-dose corticosteroids, leading to significant improvement.
Discussion
The temporal association between SCIT initiation and symptom onset raises the question of whether SCIT played a role in unmasking latent autoimmunity or if SLE developed independently. Possible mechanisms include:
1. Immune Dysregulation: SCIT alters immune homeostasis, potentially disrupting self-tolerance in at-risk individuals.
2. Molecular Mimicry: Cross-reactivity between allergen peptides and self-antigens could trigger autoimmunity.
3. Th1/Th2 Shift: The transition from Th2 dominance to a Th1/Th17-driven response may contribute to autoimmune activation.
Although SCIT-induced autoimmunity is rare, this case highlights the need for vigilance, particularly in patients with genetic susceptibility. Sublingual immunotherapy (SLIT) similarly modulates immunity, but its potential role in autoimmune activation remains unclear.
Conclusion
Clinicians should remain alert to potential autoimmune manifestations in SCIT patients. Pre-treatment screening for ANA and other autoimmune markers may be beneficial in selected cases, particularly those with a strong family history. Further research is needed to determine whether SCIT can unmask autoimmune diseases or if this case represents an incidental association.
