Endotyping Cellular and Humoral Immunoreactivity against Pollen and Citrus Fruits in Patients with Non–IgE-mediated Rhinoconjunctivitis

Background: Allergies to citrus fruits are often associated with pollinosis due to cross-reactivity among pollen and food allergens (fruit-pollen syndrome) displayed in patients with several conditions, such as allergic rhinoconjunctivitis.

Aim: To evaluate the potential of the Tube Titration of Precipitins (TTP) and the Leukocyte Adherence Inhibition Test (LAIT) to discriminate cellular and humoral immunoreactivity against two Citrus spices (orange and lemon) and a pollen extract in patients with non–IgE-mediated allergic rhinoconjunctivitis.

Study Design: We retrospectively examined the medical charts of two cohorts of patients clinically diagnosed with non–IgE-mediated rhinoconjunctivitis with clinical suspicion of hypersensitivity against Citrus spices and pollen, who were investigated with the help of TTP or LAIT, simultaneously tested against individual extracts of orange, lemon and pollen.

Methodology: The registered results of TTP and LAIT were distributed in ranges through a cascade distribution chart to outline the variability of the results. Dispersion graphs plotting the results of LAIT between the results of each pair of allergens were presented. The statistical significances were calculated.

Results: The TTP for the pollen, orange, and lemon extracts showed a distribution concentrated on the higher dilutions, precluding an adequate differentiation among patients’ immunoreactivities. On the contrary, the LAIT results showed a wide distribution of results, demonstrating a better potential to differentiate patients and predict hypersensitivity. While the TTP results showed a slight correlation between the paired tests (Pearson’s correlation coefficient between r = 0.007 to 0.11), the LAIT results demonstrated a significant moderate correlation between the paired assays, projecting a better potential to predict cross-reactivity among the allergens (Pearson’s correlation coefficient between r = 0.43 to 0.56).

Conclusion: Our preliminary results support that the TTP and LAIT performed with orange, lemon, and pollen extracts can potentially discriminate diverse degrees of humoral and cellular immunoreactivity in non–IgE-mediated allergic rhinoconjunctivitis patients.