The investigators wish to characterize alterations in the architecture and function of immune cells in patients with a primary immunodeficiency that also develop inflammatory bowel disease. In addition, The investigators' goal is to characterize the microbiome of these patients, in order to determine whether specific microbial alterations are related to inflammation.

The pathogenesis of inflammatory bowel diseases (IBD), like Crohn's disease and ulcerative colitis is complex and is thought to be related to genetic, environmental and microbial alterations that lead to a hyperactive/dysregulated immune system that mediates tissue damage. In rare cases, IBD can develop in patients with primary immunodeficiencies (PID) who develop severe, atypical or recurrent infections. The bowel disease in these patients can present after they develop infectious complications but also prior to that. The goal of the current study is to characterize immune function in patients with PID and IBD in order to identify alterations in pro-inflammatory and regulatory pathways.

The investigators will obtain blood samples from PID patients with IBD in order to perform deep immune profiling using various techniques such as flow cytometry, ELISA and others. Moreover, the investigators wish to characterize the microbiome of these patients. This multi-disciplinary approach will advance our understanding why specific patients with an immunodeficiency develop an IBD-like phenotype.

Inclusion Criteria:

• age <18 years
• diagnosis of an immunodeficiency
• suspected or confirmed IBD

Exclusion Criteria:

• none

Patients with a known or unknown immunodeficiency who develop inflammatory bowel disease or are suspected to have such a condition.