H1° histone and differentiation of dendritic cells. A molecular target for tumor-derived factors

Dendritic cells (DC) play a central role in antitumor immune responses. Abnormal differentiation of DC and their inability to stimulate T cells are important factors in tumor escape from immune-system control. However, the mechanisms of this process remain elusive. Here, we have described one possible molecular mechanism that involves replacement linker histone H1°. A close association between expression of H1° and DC differentiation in vitro has been found. DC production in H1°-deficient mice was decreased significantly, whereas generation and function of macrophages, granulocytes, and lymphocytes appear to be normal. However, these mice had a significantly reduced response to vaccination with antigens. Tumor-derived factors considerably reduced h1° expression in hematopoietic progenitor cells. We have demonstrated that transcription factor NF-κB is involved actively in regulation of h1°. Thus, H1° histone may be an important factor in normal DC differentiation. Tumor-derived factors may inhibit DC differentiation by affecting H1° expression.