Table 3.

Regulatory T cell (Tregs) properties that promote their persistence as a cellular reservoir of HIV-1

Characteristics promoting survival	•Biochemical characteristics similar to an anergic cell population	[26]
	•FOXP3 expression inhibits HIV long-terminal repeat transcription favouring latency	[32]
	•CTLA-4 activation upregulates Bcl-2, promoting resistance to apoptosis	[33]
	•FOXP3 expression and CTLA-4 activation downregulate Fas-FasL production making Tregs resistant to apoptosis	[33,34]
Immunosuppressive properties preventing elimination	•Direct cellular interactions with CD8+ T cells suppresses granzyme-B and perforin release	[6]
	•IL-2R consumption of IL-2 prevents CD4+ T cell activation and induces apoptosis; this process also inhibits CD8+ T cell differentiation	[15,38]
	•Production of inhibitory cytokines such as TGF-β and IL-10	[36,37]
	•Blockade of B7-CD28 co-stimulation inhibits dendritic cell maturation and antigen presentation	[18]
	•CD39 and CD73 ectonucleotidases convert ATP to adenosine, activating a variety of inhibitory immune pathways	[18]