. 2021 Sep 16;12:731100. doi: 10.3389/fimmu.2021.731100

Table 3.

Tfh cell responses in various vaccine candidates of SARS-CoV-2.

Vaccine candidates	Phenotypes	Function	Antibody isotypes	References
mRNA vaccines
mRNA-1273	IL-21⁺CXCR5⁺PD−1⁺ICOS⁺Tfh cells expansion.	Induce robust and specific antibody responses including neutralizing antibody.	IgA, IgG	(166)
full SΔ furin mRNA	B220^-CD4⁺CD44^hiCD62L^-CXCR5⁺Bcl-6⁺ Tfh cells, B220^-CD4⁺CD44^hiCXCR5⁺PD-1^hi IL-21⁺Tfh cells, B220^-CD4⁺CD44^hiCXCR5⁺Bcl-6⁺ ICOS⁺Tfh cells B220^-CD4⁺CD44^hiCXCR5⁺PD-1^hi IFN-γ⁺Tfh cells notable expansion.	Elicit potent SARS-CoV-2-specific GC B responses, induce robust and specific antibody responses including neutralizing antibody.	IgG1, IgG2a, IgG2b,	(167) (167)
RBD mRNA (receptor binding domain, RBD)	B220^-CD4⁺CD44^hiCD62L^-CXCR5⁺Bcl-6⁺ Tfh cells, B220^-CD4⁺CD44^hiCXCR5⁺PD-1^hi IL-21⁺Tfh cells, B220^-CD4⁺CD44^hiCXCR5⁺Bcl-6⁺ ICOS⁺Tfh cells, B220^-CD4⁺CD44^hiCXCR5⁺PD-1^hi IFN-γ⁺Tfh cells notable expansion	Elicit potent SARS-CoV-2-specific GC B responses, induce robust and specific antibody responses including neutralizing antibody.	IgG1, IgG2a, IgG2b,	(167) (167)
BNT162b2 mRNA vaccine	AIM⁺CXCR5⁺CD45RA^-CD3⁺cTfh cells expansion, AIM cells include CD69⁺OX40⁺ or CD69⁺CD40L⁺ orCD69⁺4-1BB⁺ or OX40⁺4-1BB⁺ or CD40L⁺4-1BB⁺ or CD40L⁺OX40⁺	Positively correlate with anti-spike-specific IgA and IgG titers.	IgA, IgG	(168)
Protein vaccines
rRBD-AddaVax	B220^-CD4⁺CD44^hiCD62L^-CXCR5⁺Bcl-6⁺ Tfh cells, B220^-CD4⁺CD44^hiCXCR5⁺PD-1^hi IL-21⁺Tfh cells B220^-CD4⁺CD44^hiCXCR5⁺PD-1^hi IL-4⁺Tfh cells slight expansion	Delay to elicit potent SARS-CoV-2-specific GC B responses, induce robust and specific antibody responses including neutralizing antibody.	IgG1,	(167)
NVX-CoV2373	CXCR5⁺PD-1⁺CD4⁺Tfh cells expansion	Induce specific antibody responses including neutralizing antibody.	IgG	(169)
Spike (S) and receptor binding domain (RBD) protein subunit vaccine	CXCR5⁺⁺BCL-6⁺CD4⁺CD3⁺B220^-Tfh cells expansion	Induce specific antibody responses including neutralizing antibody.	IgG	(170)
StriFK-FH002C	PD-1⁺CXCR5⁺CD4⁺Tfh cells expansion	Induce specific antibody responses including neutralizing antibody.	IgG, IgG1, IgG2a, IgG2b	(171)

Tfh, follicular helper T cell; cTfh, circulating Tfh cell.