Fungal-specific IgG responses in allergic conjunctivitis: comparison with IgE and immunological implications

Immunoglobulin G (IgG) is the most abundant antibody class in the bloodstream and is characterized by a long half-life compared to other immunoglobulins. While IgG plays a key role in host defense against infections, it is also known to be elevated in chronic inflammatory conditions. This study aimed to evaluate serum levels of fungus-specific Immunoglobulin E (IgE) and IgG antibodies in patients with allergic conjunctivitis and to investigate their associations with disease severity and sensitization status.

A total of 40 patients with allergic conjunctivitis and 20 healthy controls were enrolled. Serum levels of specific IgE and IgG antibodies against four common fungi-Alternaria, Aspergillus, Cladosporium, and Penicillium-were measured. These values were compared with skin prick test (SPT) results and clinical severity scores for allergic conjunctivitis (0-30 scale).

Patients with allergic conjunctivitis exhibited significantly higher positivity rates and serum titers of both IgE and IgG against all four fungal antigens compared to controls (p < 0.05). Notably, IgG titers were significantly higher than IgE titers across all fungal antigens (p < 0.05). IgG levels demonstrated stronger correlations with SPT positivity (correlation coefficients r = 0.95-0.97 vs. r = 0.60-0.89 for IgE) and allergic conjunctivitis severity scores (r = 0.35-0.60 vs. r = 0.23-0.43 for IgE, p < 0.001).

Serum fungus-specific IgG antibodies may serve as useful biomarkers reflecting the severity of allergic conjunctivitis. Given that mucosal barrier dysfunction has been implicated in allergic inflammation, the findings suggest that hypersensitivity reactions to fungal elements due to impaired barrier function may contribute to disease pathogenesis.