RÉSUMÉ
This study aimed to identify the species of insects that might be responsible for papular urticaria [PU] and to study some immunological aspects of the disease among affected atopic patients [AP] and non- atopic patients [NAP]. This study included 40 urban pediatric patients with PU of different duration and ten healthy age matched control subjects. It was concluded that during summer, Culex pipiens is the most common cause of PU in urban areas of Suez-Canal region, followed by human fleas. Antibodies of the IgE class play a central role in insect bite allergy and PU, while antibodies of IgG class may be formed to either sensitize mast cells and basophils for a short period or help natural desensitization during a long-term exposure. Helper T-lymphocytes may initiate the immunologic response of PU, while suppressor T-lymphocytes may serve to terminate it