Introduction: Botulinum toxin A (BoT/A) treatment failure (BTF) affects patients subjected to repeated BoT/A exposure for cosmetic indications. BoT/A's general formulation contains core BoT/A and complexing proteins. BTF may be caused by antibody-induced treatment failure. Antibodies against core BoT/A can occur; however, anti-complexing protein antibodies have never been demonstrated, and tools for anti-complexing protein antibody detection have not been developed. The aim of this study was to evaluate immune involvement in BoT/A-nonresponsive patients.
Methods: Patients suspected of nonresponsiveness to BoT/A for cosmetic indications were recruited. All volunteers were categorized as BoT/A-responsive or BoT/A-tolerant according to frontalis testing with onabotulinumtoxinA (onaA). Twenty-two BoT/A-tolerant volunteers were recruited separately for frontalis testing with incobotulinumtoxinA (incoA). Anti-BoT/A and anti-complexing protein antibodies were quantified by special ELISA using sera from blood sampled before and after frontalis testing.
Results: Significantly higher levels of IgG against complexing protein were detected in onaA-tolerant sera but not in onaA-responders, leading to proposals that anti-complexing protein antibodies could cause onaA unresponsiveness. Some onaA-tolerant patients according to frontalis test with incoA were responsive to incoA. Newly developed absorption ELISA confirmed that incoA-responsive sera predominantly contained IgG against complexing proteins, whereas incoA-tolerant sera contained significant levels of IgG against core BoT/A. The presence of anti-complexing protein antibodies higher than 90.75% in sera of onaA-tolerant patients could respond to incoA. The ELISA technique might be employed as a tool to predict incoA responsiveness. Our frontalis testing after incoA treatment showed that anti-incoA IgG levels were not increased by incoA.
Conclusions: BoT/A-exposed patients may develop antibodies against core botulinum toxin and complexing proteins. Our study is the first to demonstrate that anti-complexing protein antibodies cause BTF. High levels of antibodies against complexing proteins can cause onaA unresponsiveness, although some patients were still incoA-responsive. Our developed ELISA to detect anti-complexing protein antibodies can determine whether onaA-tolerant patients respond to incoA without incoA frontalis testing.
Keywords: Antibody; Botulinum toxin A; Complexing protein; ELISA; Secondary botulinum toxin A treatment failure.