Investigating IgE cross-reactive antibody responses in invertebrates: Use of recombinant tropomyosin from cockroach and Ascaris lumbricoides

Abstract

Invertebrates: Use of Recombinant Tropomyosin From Cockroach and Ascaris lumbricoides A. B. R. Santos1, V. S. F. Sales2, V. P. L. Ferriani3, M. D. Chapman4, L. K. Arruda1; 1Internal Medicine, School of Medicine of Ribeirao Preto University of Sao Paulo, Ribeirao Preto, BRAZIL, 2Pharmacology, Federal University of Rio Grande do Norte, Natal, BRAZIL, 3Pediatrics, School of Medicine of Ribeirao Preto University of Sao Paulo, Ribeirao Preto, BRAZIL, 4Indoor Biotechnologies Inc, Charlottesville, VA. RATIONALE: We have previously shown that infection with A. lumbricoides is an important risk factor for wheezing in children living in Brazil. We aimed to use recombinant tropomyosins to investigate IgE antibody responses to Ascaris and cockroach. METHODS: cDNA coding for A. lumbricoides tropomyosin was subcloned into pPIC-9 vector and expression of the recombinant protein was carried out in the Pichia pastoris system. Recombinant tropomyosins from A. lumbricoides and cockroach were used in chimeric ELISA to quantitate specific IgE antibodies in panels of sera from 137 children living in a parasite-endemic area, and 188 patients with asthma and/or rhinitis allergic to cockroach from our clinic. RESULTS: In children from a parasite-endemic area, IgE to tropomyosin was found in 99/137 (72.2 %) of sera; of those, 57 (41.6%) had IgE to both Ascaris and cockroach tropomyosin. Geometric mean (GM) levels of IgE to Ascaris and cockroach tropomyosin were 7.5 IU/mL and 8.1 IU/mL, respectively. There was a significant correlation of levels of IgE to A. lumbricoides and cockroach tropomyosin (r = 0.7, p < 0.0001). Among cockroach allergic patients, presence of IgE to tropomyosin was found in 79/188 (42%), and of those, 48/188 (25.5%) presented IgE to both Ascaris and cockroach tropomyosin, with GM levels of 2.56 UI/mL and 5.4 UI/mL , respectively. There was also a significant correlation of levels of IgE antibodies to both tropomyosins (r = 0.58, p < 0.0001). CONCLUSION: Tropomyosins from invertebrates are important IgEbinding proteins. Recombinant tropomyosins could be used to investigate IgE antibody responses to Ascaris and cockroach. Funding: FAPESP, CNPq