IL1B and Behcet disease: Tukey’s post-hoc tests for multiple comparisons showed that serum IL-1β levels were elevated specifically in HERV-W ENVpos BD subjects (i.e. in the BD/CL2 subgroup), as compared to HERV-W ENVneg BD (BD/CL1) subjects (p < 0.01) and HC subjects (p < 0.001; Fig. 2C).