Clinical review: flow cytometry perspectives in the ICU - from diagnosis of infection to monitoring of injury-induced immune dysfunctions

Table 1 Immune dysfunctions in septic patients: potential biomarkers

Response		Biomarker	Flow cytometry technique
Innate immune response	Functional testing	↓ ex vivo cytokine production after TLR agonist stimulation	Cytometric bead array
	Plasma cytokines	↑ IL-10	Cytometric bead array
	Cell surface marker expression	↓ mHLA-DR	Cell surface staining
		↓ CD14, CD86, GM-CSFR, CX3CR1, and so forth
	Apoptosis	Depolarized mitochondria	Cell surface staining
		↓ CD14
Adaptive immune response	Functional testing	↓ proliferation after antigenic or nonspecific stimulation	CFSE probes
	Cell surface marker expression	↑ inhibitory receptors: PD-1, CTLA4, CD47, and so forth	Cell surface staining
		↓ co-activator receptors: CD28, CD3
		↑ % CD4⁺CD25⁺ regulatory T cells
	Apoptosis	↓ T-cell count	Cell surface staining
		↑ Annexin V staining	Cell surface staining
		↓ Bcl2 expression protein/gene	Intracellular staining
		Bax/Bcl-xl or Bax/Bcl2 ratios

CFSE, carboxyfluorescein succinimidyl ester; GM-CSFR, granulocyte-macrophage colony-stimulating factor receptor; mHLA-DR, circulating monocyte human leukocyte antigen-DR expression; PD-1, programmed death 1; TLR, Toll-like receptor.

ISSN: 1364-8535