NF-κB inhibitors suppress spontaneous lymphoproliferation in HAM/TSP PBMCs. Proliferation was measured by either tritiated thymidine incorporation or CFSE dilution in PBMCs from subjects with HAM/TSP. (A) Percent inhibition of tritiated thymidine incorporation (day 4) in HAM/TSP PBMCs (n = 3) treated with increasing concentrations of the regioisomer PBS-1143 (control), or the NF-κB inhibitors DHMEQ and PBS-1086 compared with untreated PBMCs. Error bars indicate standard deviation. (B) Representative FACS plots showing CFSE dilution in untreated, control regioisomer PBS-1143 (10μM)– or PBS-1086 (10μM)–treated HAM/TSP PBMCs after 5 days of culture.