Chloroquine inhibits accessory cell presentation of soluble natural and synthetic protein antigens

CpG Motifs in Bacterial DNA Activate Leukocytes Through the pH-Dependent Generation of Reactive Oxygen Species

B cells and monocytes endocytose DNA into an acidified intracellular compartment. If this DNA contains unmethylated CpG dinucleotides in particular base contexts (CpG motifs), these leukocytes are rapidly activated. We now show that both B cell and monocyte-like cell line responses to DNA containing CpG motifs (CpG DNA) are sensitive to endosomal acidification inhibitors; they are completely blocked by bafilomycin A, chloroquine, and monensin. The specificity of these inhibitors is demonstrated by their failure to prevent responses to LPS, PMA, or ligation of CD40 or IgM. Acidification of endosomal CpG DNA is coupled to the rapid generation of intracellular reactive oxygen species. The CpG DNA-induced reactive oxygen species burst is linked to the degradation of IκB and the activation of NFκB, which induces leukocyte gene transcription and cytokine secretion. These studies demonstrate a novel pathway of leukocyte activation triggered by CpG motifs.

Uptake of chloroquine and hydroxychloroquine by human blood leucocytes in vitro: relation to cellular concentrations during antirheumatic therapy

The accumulation of chloroquine and hydroxychloroquine in unfractionated mononuclear cells and in purified monocytes, lymphocytes, and neutrophil polymorphonuclear leucocytes (PMN) was measured in vitro. Accumulation of both drugs in leucocytes was time and dose dependent. Cellular levels comparable to those found during antirheumatic therapy were achieved by preincubation for 60 minutes with up to 0.1 mM chloroquine or hydroxychloroquine.