Immune cell study sheds light on childhood disease

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

General inclusion criteria for all sub-populations included in the study * The child (with age- and comprehension-skill-appropriate information) and parents (or persons exercising parental authority) have been informed about the implementation of the study, its objectives, constraints and patient rights * The child (depending on age) and parents (or persons exercising parental authority) have given their free and informed consent and signed the consent * The patient must be insured or beneficiary of a health insurance plan Inclusion criteria for population A: Henoch Schönlein purpura, acute episodes * The diagnosis of Henoch Schönlein purpura was made by a physician according to the EULAR / PRES / PRINTO 2010 criteria (purpura predominantly on the lower limbs associated with one of the following criteria: abdominal pain, arthralgia or arthritis, kidney damage or suggestive histology (immune deposits dominated by Immunoglobulin A (IgA)) * The patient is not treated via immunosuppression (steroids or other immunosuppressive / biotherapy) and has not been treated like this for at least 15 days Inclusion criteria for population B: Henoch Schönlein purpura in remission * The diagnosis of Henoch Schönlein purpura was made by a physician according to the EULAR / PRES / PRINTO 2010 criteria * The patient has has a Henoch Schönlein purpura episode in the past, and no longer has any symptoms of the disease * The patient is not treated via immunosuppression (steroids or other immunosuppressive / biotherapy) and has not been treated like this for at least 15 days Inclusion criteria for population C: controls * Subjects free from infectious, inflammatory or autoimmune diseases * Candidates for elective surgery (circumcision, urological surgery, removal of tonsils and adenoids) Exclusion Criteria: * The patient is participating in another interventional study or is in an exclusion period determined by a previous study * The child refuses to participate in the study * Parents (or persons with parental responsibility if any) refuse to sign the consent * It is impossible to correctly inform the patient or his/her parents (or persons with parental authority if any) * The patient has another inflammatory or autoimmune disease * Patient on immunosuppressive / biotherapy treatments