ABSTRACT
BACKGROUND: The induction of protein tyrosine kinases (PTKs) is known to be a key element in the activation of lymphocytes. OBJECTIVE: Because immunologic mechanisms are important in the pathogenesis of psoriasis, we examined the time course of tyrosine-phosphorylated proteins (p-tyr) as a marker for cellular PTK activity in phytohemagglutinin (PHA)-stimulated T cells of psoriatic patients and healthy controls. METHODS AND RESULTS: PHA-stimulated T cells from both groups expressed peaks of p-tyr after 15 min and 4 h. In T cells from psoriatics, the 15-min peak was smaller but the 4-hour peak reached an enormous maximum, which was 270% higher than the basic p-tyr value. PHA-stimulated T cells were additionally treated with psoriasis-provoking drugs (lithium, chloroquine, propranolol and ethanol) and the two immunosuppressive drugs cyclosporin A and FK 506. Lithium and propranolol were able to increase the p-tyr level after 15 min in PHA-stimulated T cells from psoriatics in contrast to controls. Chloroquine and ethanol did not have a significant effect on T cells of both groups. CsA markedly diminished the phosphorylation of intracellular tyrosines in T cells of psoriatics and controls, whereas FK 506 diminished the p-tyr level in controls only slightly. CONCLUSION: We have characterized important differences in p-tyr phosphorylation activities of psoriatic T cells compared to controls. This could be a hint to explain the known abnormalities of psoriatic T cells.
Subject(s)
Protein-Tyrosine Kinases/metabolism , Psoriasis/metabolism , T-Lymphocytes/drug effects , T-Lymphocytes/metabolism , Tyrosine/metabolism , Adolescent , Adult , Aged , Case-Control Studies , Cells, Cultured , Chloroquine/pharmacology , Cyclosporine/pharmacology , Ethanol/pharmacology , Female , Humans , Immunosuppressive Agents/pharmacology , Irritants/pharmacology , Lithium/pharmacology , Lymphocyte Activation/drug effects , Male , Middle Aged , Phosphorylation , Phytohemagglutinins/pharmacology , Propranolol/pharmacology , Psoriasis/immunology , Psoriasis/physiopathology , T-Lymphocytes/immunology , Tacrolimus/pharmacology , Time Factors , Tyrosine/drug effectsABSTRACT
Visual search and decision-making performance together with subjective fatigue were investigated over a 4-hr time block as a function of display foreground and background chromaticity using colors matched for brightness. Although some small differences in performance related to chromaticity were observed, these were not exacerbated over time. On the basis of the performance data obtained and the subjective reports, there was no support for the general recommendation to avoid the use of red and blue stimuli, either alone or in combination, in CRT displays.
