. Author manuscript; available in PMC: 2022 Jul 1.

Published in final edited form as: Pediatrics. 2022 Jan 1;149(1 Suppl 1):S91–S98. doi: 10.1542/peds.2021-052888N

TABLE 1.

Criteria for Immune System Dysfunction in Pediatric Critical Illness

Organ System	Criterion For Organ Dysfunction	Suggested Thresholds	Conditions	Severity

Immune	Peripheral absolute neutrophil count	<500 cells/μL	None	Not graded
Immune	Peripheral ALC	<1000 cells/μL	None	Not graded
Immune	CD4⁺ T-lymphocyte count	<750 cells/μL	Age <1 y	Not graded
		<500 cells/μL	Age 1–5 y	Not graded
		<200 cells/μL	Age ≥6 y	Not graded
Immune	CD4⁺ T-lymphocyte percentage of total lymphocytes	<26%	Age <1 y	Not graded
		<22%	Age 1–5 y	Not graded
		<14%	Age ≥6 y	Not graded
Where clinically available^a
Immune	Monocyte HLA-DR expression	<30%	None	Not graded
Immune	Ex vivo LPS-induced TNFα production capacity	Below manufacturer-provided thresholds	None	Not graded

These tests may be clinically available outside the United States.