Increased levels of HMGB1 in the plasma of lupus TC mice can induce production of inflammatory cytokines by BM cells and promote myeloid development. (A) Levels of HMGB1 detected in the plasma of healthy and lupus TC mice. Each symbol shows data from 1 mouse. (B) B6 BM cells were cultured with or without 500 ng/mL HMGB1 for 24 hours. Relative expression levels of cytokines were quantified by qRT-PCR and are shown as the ratio of each gene transcript in the presence versus absence of HMGB1 after being normalized to the level of β-actin. (C) Hematopoietic cytokines in the methylcellulose-based medium were diluted to establish a suboptimal condition (10% MethoCult M3434) under which the number of CFU reduced to approximately 50% of those formed in the optimal medium (100% MethoCult M3434). Colonies formed under the suboptimal condition with serum from lupus TC mice or with different doses of HMGB1 were counted at day 14 of culture and presented as bars with mean ± SD from 3 independent experiments. *P < .05; **P < .01.