Fig. 2: IFNαR Blockade increases vaccine-specific CD8⁺ T cell responses.

A Serum levels of IFNα 2 and 4 at various timepoints after immunization with 2.5 μg of mRNA-LNP from four C57BL/6J wild-type mice (WT) pooled together. B (Left) Surface expression of IFNαR1 from mice given 250 μg of MAR1-5A3 (αIFNαR, red) (IP), or no MAR1-5A3 (black) and compared to an IFNαR knockout mouse (blue). (Right) Representative plot showing IFNαR1 MFI of each mouse at days 1, 3, 5, 7, and 9 post injection of MAR1-5A3 (red, n = 5) compared to a WT mouse with no MAR1-5A3 injection (black, n = 1) or an IFNαR knockout mouse (blue, n = 1). C (Left) Representative flow plot of splenic CD11c⁺MHCII⁺ DCs expressing eGFP from WT mice with or without MAR1-5A3. (Right) Percentage of eGFP expression in splenic DCs 24 h post mRNA-LNP immunization (5 μg eGFP mRNA-LNP or 2.5 μg OVA mRNA-LNP IV) in WT mice (black, n = 6), or WT mice given MAR1-5A3 prior to immunization (red, n = 8). D (Left) Representative flow plot showing CD40⁺CD86⁺ splenic DCs after immunization with mRNA-LNP with or without MAR1-5A3. (Right) Percentage of CD40⁺CD86⁺ splenic DCs from mice in Fig. 2C. E (Left) Representative flow plots of SIINFEKL-H2-K^b (OVA) specific CD8⁺ T cells. (Right) Percentage of OVA specific CD8⁺ T cells from WT mice (black, n = 8) and WT mice given MAR1-5A3 (red, n = 11). 2.5 μg of mRNA-LNP was administered IV 24 h after MAR1-5A3. F (Left) Representative flow plot showing PD-1 expression of OVA specific TCRβ⁺CD8α⁺ T cells. (Right) PD-1 expression of TCRβ⁺CD8α⁺ T cells from mice in Fig. 2E. G (Left) Representative flow plot of splenic CD11c⁺MHCII⁺ DCs expressing fluorescent LNP from WT mice with or without MAR1-5A3. (Right) Percentage of LNP expression in splenic DCs 24 h post mRNA-LNP immunization (5 μg DiD incorporated LNP eGFP mRNA-LNP or 2.5 μg OVA mRNA-LNP IV) in WT mice (black, n = 10), or WT mice given MAR1-5A3 prior to immunization (red, n = 11). Error bars in (A) indicate ± SD. All bars in (C)–(G) indicate the mean. Data in (C) and (E) were compared using a Mann–Whitney test. Data in (D) were compared with either an unpaired two-tailed students T test or a Mann–Whitney test. Data in (F) and (G) were compared by an unpaired two-tailed students T test.