Private specificities of CD8 T cell responses control patterns of heterologous immunity

Kim, Sung-Kwon; Cornberg, Markus; Wang, Xiaoting Z.; Chen, Hong D.; Selin, Liisa K.; Welsh, Raymond M.

However, in contrast with PV infection, challenge of LCMV-immune mice with VV led to a much less predictable response, where T cells specific to different epitopes were favored in different mice ( Fig. 1 B) . We summarized the VV-induced changes in the hierarchies of LCMV-specific CD8 T cells in 26 examined mice in Table I . Several distinctive features of heterologous immunity during VV infection were noted. First, the increase in the number of putatively cross-reactive LCMV epitope-specific CD8 T cells was less dramatic and more subtle than the expansion observed during PV infection. In LCMV-immune mouse no. 11, although the frequencies of NP396-, GP33-, GP276-, and GP118-specific CD8 T cells were dramatically and somewhat comparably reduced, the frequency of NP205specific CD8 T cells remained about the same ( Fig. 1 B, 105% of LCMV-immune mice). This maintenance of frequency by the NP205-specific T cells actually represents an increase in number, considering an overall increase in the CD8 T cell percentage upon VV infection. In 26 LCMVimmune control mice, the percentage of CD8 in the PBLs was 10.1 Ï® 2.3%, whereas the percentage of CD8 cells in the VV-challenged LCMV-immune mice was 20.5 Ï® 4.5%. Furthermore, given the fact that the total numbers of leukocytes were also routinely increased in the spleen after VV infection (LCMV-immune Ï­ 6.4 Ï® 2.4 Ï« 10 7 vs. LCMVimmune Ï© VV day 12 Ï­ 15 Ï® 10 7 ) and well reflected in peripheral blood, the increase in number is expected to be greater.