Induction of IgG2 and IgG4 B‐cell memory following sublingual immunotherapy for ryegrass pollen allergy

Induction of IgG2 and IgG4 B‐cell memory following sublingual immunotherapy for ryegrass pollen allergy:

Abstract

Background

Whilst treatment for atopic rhinitis is aimed mostly to relieve symptoms, only allergen‐specific immunotherapy (AIT) is targeted to modify the natural history of allergic diseases. This results in sustained clinical tolerance, even when treatment has stopped. The immunomodulatory effects of AIT are attributed mainly to increased regulatory T cell function and increased allergen‐specific IgG₄, yet little is known about the effect on the memory B cell compartment.

Objective

We aimed to examine the effects of AIT on the IgE and IgG subclass expressing memory B cells.

Methods

We recruited 29 patients with atopic seasonal rhinoconjunctivitis and performed a longitudinal analysis of the peripheral immune compartment before, during and after sublingual immunotherapy (SLIT) for allergy to temperate grass pollen, predominantly to ryegrass pollen (RGP; Lolium perenne). Using flow cytometry on peripheral blood mononuclear cells and serum immunoassays we analyzed the effects of a 4‐month pre‐seasonal treatment regimen comprising two or three courses in consecutive years on circulating IgE⁺ and IgG⁺ memory B cells and allergen‐specific Ig levels.

Results

SLIT increased RGP‐specific serum IgG₂ and IgG₄, as well as the frequencies of IgG₂⁺ and IgG₄⁺ memory B cells, whereas no effect was observed on the IgE⁺ memory B‐cell compartment. Furthermore, SLIT enhanced proportions of regulatory T cells specific to RGP. These changes were associated with clinical improvement.

Conclusion

Our data provide evidence for immunological effects of SLIT on B‐cell memory. Skewing responses towards IgG₂ and IgG₄ subclasses might be a mechanism to suppress IgE‐mediated allergic responses.