Fig. 3

NP-specific CTL responses induced by live influenza infection (A) or NP DNA immunization (B) are restricted by the MHC haplotype of the BM APCs in chimeras

Spleen cells from chimeric mice immunized by intranasal infection with live influenza virus or by i.m. injection with NP DNA were restimulated in vitro for 7 days with F1 spleen cells pulsed with either H-2D^b-restricted peptide NP366–374 or H-2K^d-restricted peptide NP 147–155. The resulting effector cells were tested against EL4 (H-2^b) cells pulsed with the H-2D^b peptide or P815 (H-2^d) cells pulsed with the H-2K^d peptide. Open circles represent the lysis of P815 cells pulsed with H-2K^d peptide by the spleen cells restimulated with H-2D^b peptide (allele-mismatched restimulation) and closed circles represent the lysis of P815 cells pulsed with H-2K^d peptide by the spleen cells restimulated with H-2K^d peptide (allele-matched restimulation). Open triangles represent the lysis of EL4 cells pulsed with H-2D^b peptide by the spleen cells restimulated with H-2K^d peptide (allele-mismatched restimulation) and closed triangles represent the lysis of EL4 cells pulsed with H-2D^b peptide by the spleen cells restimulated with H-2D^b peptide (allele-matched restimulation). The data shown are representative of three independent experiments. The percent lysis by spleen cells from mock-immunized and mock-infected control mice was less than 15%, and the percent lysis of the nonspecific control targets (P815 cells pulsed with H-2D^b-restricted NP366-374 peptide or EL4 cells pulsed with H-2K^d-restricted NP147–155 peptide) ranged from 7% at an E:T ratio of 2:1 to 15.6% at an E:T ratio of 60:1 (results not shown).