The role of dendritic cells in COVID-19 infection

Figures & data

Figure 1. The role of dendritic cells in COVID-19 infection. When dendritic cells come in contact with viruses, they are stimulated and play different roles. Positive effect: It means that dendritic cells exert immune functions and play an important role in the body's resistance to viral invasion, connecting innate and specific immunity. Negative effect: It refers to the fact that viral infection of dendritic cells leads to decrease in the number and loss of function of dendritic cells, which is detrimental to the elimination of the invading virus by the organism.

Table 1. DC subtype and function.

DC subtype		Function
pre-DCs [20–23]	cDC1	cDC1s have a high intrinsic capacity to cross-present antigens, due to expression of the CLEC9A c-type lectin [24], and activate CD8+, Thl, and NK cells [25].
	cDC2	cDC2s express various pattern recognition receptors (PRRs) and can promote a wide range of immune responses, especially CD4+ T-cell responses [26].
	pDC	pDCs express high levels of endosomal nucleic acid sensing Toll-like receptors (TLRs) TLR7 and TLR9. pDCs respond to these nucleic acids with massive secretion of IFN-I and also produce type Ill interferon (IFN-λ or IL-28/lL-29) and additional cytokines (e.g. TNF-a) and chemokines [27–29]
	mo-DC	mo-DCs have a key role in inflammation [30] and infection [31], often termed “inflammatory mo-DC” [18].

DCs encompass a heterogeneous family of bone marrow-derived cells and are found in the peripheral blood, lymphoid organs, and tissues. According to the most recent DC classification, conventional DCs (cDCs) and plasmacytoid DCs (pDCs) are the two main functional DC subtypes. Conventional DCs encompass a new subset with monocyte-like characteristics, named monocyte-derived mo-DCs or DC3.

Figure 2. The role of dendritic cells in adaptive immune responses.

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