This observation was (i) irrespective of the prior treatment history of the patient; (ii) despite a patient having already raised serum tryptase and total IgE concentrations, which could suggest underlying allergic disease or sensitivity; and (iii) irrespective of the patients’ tumour FRα expression, or presence of FRα or anti-FRα autoantibodies in the circulation (molecules which may hypothetically form an immune complex with MOv18 IgE, triggering basophil activation) (Figure 5C). Here, FOLR1 is linked to allergic disease.