T-cell and antibody responses to phospholipase A2 from different species show distinct cross-reactivity patterns.

To cite this article: Sin BA, Akdis M, Zumkehr J, Bezzine S, Bekpen C, Lambeau G, Akdis CA. T-cell and antibody responses to phospholipase A₂ from different species show distinct cross-reactivity patterns. Allergy 2011; 66: 1513-1521. Abstract Background: Secreted phospholipases A₂ (sPLA₂) represent antigens to which humans may be rarely or frequently exposed. Thus, the investigation of humoral and cellular immune responses to sPLA₂s from different species can provide a suitable model in the study of antibody and T-cell cross-reactivity. Methods: Specific IgE, IgG₁, IgG₄, and IgA antibodies were analyzed by ELISA against sPLA₂s from pancreas of Bos taurus (BT), Apis mellifera (AM) bee venom, Daboia russellii (DR) and Naja mossambica (NM) snake venoms, and human group III (hGIII) sPLA₂ using sera of nonallergic beekeepers, AM-allergic patients, and healthy controls. T-cell cross-reactivity was investigated in PBMC, and T-cell clones (TCC) are generated against AM sPLA₂. Results: Hyperimmune and allergic individuals showed high levels of sPLA₂-specific IgG₄ and significant IgG₄ cross-reactivity between BT, DR, and NM sPLA₂s. Furthermore, IgE, IgA, and IgG₁ cross-reactivities against BT, DR, and NM sPLA₂s were also detectable in the range of 22.2-44.8%. Allergic patients showed significant T-cell proliferative response to NM sPLA₂ together with increased IFN-γ and IL-13 production even though they had never been exposed to cobra venom. Although nonallergic healthy controls show no cross-reactivity at T-cell level, they did have low levels of IgG₄ and IgA against BT, DR, and NM sPLA₂s. Human TCC spanning three major T-cell epitopes of AM sPLA₂ showed minor proliferative response to NM and hGIII sPLA₂s. Conclusions: This study shows that T cells and antibodies may show cross-reactivity between different species without being naturally exposed to sPLA₂s. [ABSTRACT FROM AUTHOR]