Chloroquine Stimulates the Mitogen-Driven Lymphocyte Proliferation in Patients with Psoriasis

Abstract

Chloroquine is known to exacerbate psoriasis. Since immunological stimuli are considered to be important for the pathogenesis of psoriasis, we compared the effects of chloroquine on cell-mediated immunity in 15 healthy control individuals and 15 patients with psoriasis. We employed the spontaneous and phytohemagglutin (PHA)-induced uptake of ³H-thymidine to measure lymphocyte proliferation. Chloroquine was added to the cultures at concentrations ranging from 0.022 to 220 μM. We found that both spontaneous and PHA-driven lymphocyte proliferations were significantly lower in patients with psoriasis (p < 0.002). The spontaneous blastogenesis in both controls and patients remained stable under chloroquine. In PHA-driven cultures in controls, 0.022––2.2 μM chloroquine had no effect, higher concentrations of the drug suppressed proliferation. In patients, 22 μM chloroquine surmounted the suppression of the PHA-induced proliferative response found in controls; moreover, 2.2––0.022 μM chloroquine increased lymphocyte proliferation by > 300% (p < 0.002). Our data indicate that in psoriasis the lower lymphocyte transformation is abnormally stimulated by the addition of pharmacological doses of chloroquine.

Association of Early-Stage Psoriasis With Smoking and Male Alcohol Consumption

“…Moreover, an effect of alcohol on lymphocyte transformation has been suggested. 35 If smoking and, possibly limited to men, al- cohol consumption cause psoriasis, the impact on public health would be far from negligible. The populationattributable fraction for smoking calculated from our study was about 0.2, indicating that about 1 in 5 cases of psoriasis may be related to smoking.…”

Tyrosine Phosphorylation in Psoriatic T Cells Is Modulated by Drugs That Induce or Improve Psoriasis

“…If immunologic mechanisms are important in the pathogenesis of psoriasis, we would expect that these drugs are able to influence immunologic mechanisms in T cells in a direct or indirect manner. Recently we could dem onstrate that chloroquine increases the phytohemagglutinin (PHA)-stimulated lymphocyte proliferation of psoriatic lymphocytes in contrast to healthy controls [16], So we were interested if chloroquine, the other psoriasis-provok ing drugs and the immunosuppressive drugs CsA and FK 506 influence the PTK-induced tyrosine phosphorylation in T cells. Furthermore we investigated the time course of tyrosine phosphorylation as a marker for intracellular tyro sine kinase activity in PHA-stimulated T cells from pso riatic patients and healthy controls.…”

Successful Treatment of Psoriasis-like Lesions in HIV Infected Patients in Uganda with Chloroquine

“…Chloroquine has also been shown to abnormally stimulate the lower lymphocyte transformation in controlled experiments in patients with and without psoriasis [40]. The molecular mechanism that has been suggested for the role of chloroquine in the psoriasis disease process is blocking of epidermal transglutaminase, an enzyme that is pivotally involved in the terminal differentiation of keratinocytes [41].…”