Figure 1. HLA transgenic mice immunized with LF generate an antigen-specific memory response to the LF protein and domains which follows an HLA hierarchy and predominantly focuses upon domains II and IV.

Mice (3–5 per HLA transgenic group) were immunised in the footpad with 25 µg LF adjuvanted with Titermax Gold. Popliteal lymph nodes were harvested on day 10 and stimulated with either (A) 25 µg of whole LF or (B) the individual LF domains. The results, expressed as SI (± standard deviation) for, HLA-DR1 (n = 4), HLA-DQ8 (n = 4), HLA-DQ6 (n = 5), HLA-DR15 (n = 4) and HLA-DR4 (n = 4), demonstrated a significant difference between strains. A significantly elevated response to LF was seen in HLA-DR1 compared to DQ6, DR15 and DR4 (p = 0.0013, One-way ANOVA, with Bonferroni's multiple comparison). Cell cultures from mice transgenic for (B) DR1, (C) DQ8, (D) DQ6, (E) DR15 and (F) DR4 were stimulated for 3–5 days with LF domains; proliferation was measured by ³H-thymidine incorporation after 5 days stimulation (B, C & D), IFNγ production was assayed by ELISpot development and enumeration after 3 days stimulation (E & F). In HLA-DR1 transgenics (B) responses to domain I were significantly lower than responses to domains II and IV (p = 0.0081, Kruskal-wallis, with Dunn's multiple comparisons), while HLA-DQ8 transgenics (C) only showed a significant difference in response between domains I and IV (p = 0.0174, Friedman with Dunn's multiple comparisons). The response to the individual domains in HLA-DQ6 (D) showed significant variance (p = 0.0002, One-way ANOVA with Tukey's multiple comparisons) with the responses to domains II and IV significantly greater than the responses to domains I or III. The response to the individual domains in HLA-DR15 (E) also differed significantly (p<0.0001, One-way ANOVA with Tukey's multiple comparisons), however, only the response to domain II was elevated compared to domains I, III and IV). Data is represented as the stimulation index (SI) calculated as the mean cpm or IFNγ production of triplicate wells in the presence of peptide divided by the mean cpm or IFNγ production in the absence of antigen. Results are given as the mean ± SD/SEM.