Primary immune deficiencies (PID) are characterized by a failure of the immune system that is not explained by any infectious, neoplastic, or iatrogenic cause. In 2015, more than 300 different inherited rare disorders were described. The occurrence of PID in adult is rare and diagnosis may be supported by the 6 ESID signs for adult. However these warnings signs are based only on expert recommendations and do not include comprehensive symptoms of PIDs. Recurrent infections, more aggressive, are the most common mode of revelation of the PID. Less frequently, autoimmune manifestation, solid tumor, lymphoproliferation tumor, chronic granulomatosis or hemophagocytic lymphohistiocytosis syndrome (HLS) may also revealed a PID. The objective of this study was to evaluate the occurrence of unknown PID in adult admitted in critical care unit and to determinate if the investigation of PID in patients with severe infections or HLS should be routinely performed in MCIU.

Inclusion Criteria:

• Aged 18-65
• Hospitalized in medical intensive care unit for :
• Severe infection without pathogen identification
• Severe infection due to encapsuled pathogen
• Opportunistic infections or unusual pathogen
• Idiopathic hemophagocytic syndrome

Exclusion Criteria:

• primary immunodeficiency already known
• secondary immunodeficiency already known (HIV, cancer, immunosuppressive or immunomodulatory treatment, nephrotic syndrome, protein-losing enteropathy, severe malnutrition before admission, cirrhosis with hepatic failure, sickle cell disease, splenectomy and moderate chronic renal failure (clearance between 30 and 59 m² min/1.73 ml)
• local-regional factors which can be responsible for infections (history of ear, nose and throat surgery or neurosurgery, history of fracture of the skull base, cystic fibrosis, chronic respiratory insufficient)

Patients aged 18 to 65, hospitalized in medical intensive care unit for a severe or opportunistic infection or an idiopathic hemophagocytic syndrome, without any known warning sign or predisposing factor, were included.