Impact of high mobility group box chromosomal protein 1 on reactivity in the presence/absence of TNFα. Proliferative responses of splenocytes from TNFα+/+ mice and from TNFα-/- mice (n = five mice per group) incubated with different doses of (a) lipopolysaccharide-free purified recombinant endotoxin-free high mobility group box chromosomal protein 1 (pHMGB1) or (b) concavalin A (con A). Box plots, 25th and 75th percentiles; horizontal solid lines, medians; horizontal hatched lines, means; vertical bars, 5th and 95th percentiles. Statistical differences were calculated using the Mann–Whitney U test. CPM, counts per minute.