T cell receptor signal strength and antigen affinity differentially regulate memory CD8+ T cell development

IL-2 inducible tyrosine kinase (Itk) is a Tec family non-receptor tyrosine kinase that is known to regulate T cell receptor signal strength (TcR) and T cell development and differentiation. TcR signal strength and antigen affinity are parameters known to regulate the development of CD8+ T cell memory. However, the intersection between TcR signal strength and antigen affinity on CD8+ memory T cell development remains unclear. Therefore, we compared the transcriptomes of WT and Itk-/- OT-1/Rag-/- CD8+ T cells at day 0 and day 7 following infection with Listeria monocytogenes expressing the SIINFEKL (N4) or SIITFEKL (T4) OVA peptide variant (different affinities for TcR) by RNA sequencing. CD44lowCD122low naïve CD8+ T cells were isolated from the spleens of 4-6 week old male and female WT and Itk-/- mice (on a OT-1/Rag-/- background) using flow sorting (day 0 timepoint). To generate an effector population, naïve CD45.2 WT and Itk-/- CD8+ T cells (0.5 million/mouse) were adoptively transferred through retro-orbital injection into CD45.1 recipients (male and female, 4-6 week old) and Listeria monocytogenes (LM) expressing the SIINFEKL (N4) or SIITFEKL (T4) OVA epitope was administered intraperiotneally 24 hours post transfer. Following infection, on day 7, donor CD8+ T cells (CD45.1-CD45.2+) were isolated through flow sorting (day 7 LMN4 and day 7 LMT4 timepoints). Donor CD8+ T cells were pooled for isolating total RNA. RNA sequencing was conducted with triplicate RNAseq libraries.