Recently, we were able to demonstrate that
Omalizumab, a humanized monoclonal
anti-IgE antibody, reduces in vitro
leukotriene (LT) release of peripheral leukocytes stimulated with
allergen in children with
allergic rhinitis undergoing allergen immunotherapy. The aim of this study was to investigate the effect of
anti-IgE in combination with specific
immunotherapy (SIT) on urinary
leukotriene E4 (
LTE4) levels. Children and adolescents with sensitization to birch and grass pollens and suffering from
seasonal allergic rhinitis were included in a phase III, placebo-controlled, multicenter clinical study. Within the four-arm study, patients were randomized to receive SIT for either birch or grass pollen and to receive either subcutaneous
anti-IgE or placebo for 24 weeks during the pollen season. From a total population of 225 children, we collected three urine samples in a subgroup of 19 children [n = 12 boys (63%); mean age 11.8 years; range 7.2-17.5 years; Group A (n = 10): SIT (grass or birch) +
anti-IgE; Group B (n = 9): SIT (grass or birch) + placebo]. Urine samples were collected before, during and at the end of treatment. Endogenous urinary
LTE4 was separated by high-performance liquid chromatography (HPLC) and determined by
enzyme immunoassay with a specific antibody. No differences in urinary
LTE4 concentrations were observed between the
anti-IgE and the placebo groups before (A: 35.2; B: 36.5 nmol/mol
creatinine), during (A: 27.0; B: 29.3) and
after treatment (A: 28.9; B: 26.5 nmol/mol
creatinine). We conclude that urinary
LTE4 levels are not helpful in monitoring patients treated with
anti-IgE and SIT.