Interpretation of Decreasing IgE Levels
A decrease in IgE levels from 1228 to 875 over a month is not clinically significant for predicting treatment efficacy or disease progression, as IgE levels do not reliably correlate with clinical response to treatment or symptom severity.
Understanding IgE Level Changes
- Changes in IgE levels do not reliably predict clinical outcomes or treatment efficacy, as efficacy is not dependent on reductions in specific IgE levels 1
- Clinical improvement in many patients develops before decreases in their IgE antibody levels occur, or in patients whose IgE levels never decrease 1
- During immunotherapy, there is typically an initial increase in specific IgE antibody levels, followed by a gradual decrease, but this pattern does not correlate with symptom improvement 1
Clinical Significance of IgE Monitoring
- Clinicians should avoid repeat allergy testing (including IgE levels) as an assessment of the efficacy of ongoing allergen immunotherapy unless there is a change of environmental exposures or a loss of control of symptoms 1
- Skin testing or serum specific IgE antibody testing during treatment is not recommended because it has not been demonstrated that skin test reactivity or specific IgE levels correlate closely with symptoms 1
- The level of specific IgE does not reliably monitor the clinical response to allergen immunotherapy 1
Better Measures of Clinical Response
- Clinical parameters, such as symptoms and medication use, are more useful measures of treatment efficacy than IgE levels 1
- Clinical improvement should be monitored through symptom scores and assessment of the number of medications required for symptom control 1
- Successful immunotherapy often results in a reduction in medication needs, which is a more reliable indicator of efficacy than changes in IgE levels 1
Special Considerations for Different IgE Levels
- Very low IgE levels (<2 IU/mL) may be associated with immune dysregulation, autoimmunity, and increased prevalence of respiratory infections 2, 3
- Studies have shown associations between very low IgE levels and malignancies, autoimmune disorders, and immune deficiencies 4
- High IgE levels are typically associated with allergic conditions, parasitic infections, and some immune deficiencies 5
Immunological Mechanisms
- Successful immunotherapy is associated with immunologic tolerance, defined as a relative decrease in antigen-specific responsiveness 1
- Treatment efficacy is more closely related to changes in T-cell responses, regulatory T-cell generation, and alterations in IgG specificity rather than changes in IgE levels 1
- Increases in allergen-specific IgG antibodies (particularly IgG4) occur with immunotherapy, but the correlation between these increases and clinical improvement is not consistently demonstrated 1
Clinical Approach
- Focus on monitoring clinical symptoms and medication requirements rather than IgE levels when assessing treatment response 1
- For patients with rhinosinusitis, note that low IgE levels (<200 μg/L) may be associated with better response to macrolide therapy 1
- Avoid making treatment decisions based solely on IgE level changes, as they do not reliably predict clinical outcomes 1