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Effects of in vitro PUVA on human leukocyte function
Abstract:
Human polymorphonuclear and monomorphonuclear leukocytes (PMNL and MMNL) were exposed in vitro to 8-methoxypsoralen (8-MOP, 0.1-80 micrograms/ml) and/or UV-A radiation (0.03-2 J/cm2) and then analysed for the following functions: chemotaxis, bactericidal activity and proliferation in response to mitogen stimulation. The functions of PMNL became depressed only at a high PUVA dose level (about 20 micrograms/ml of 8-MOP plus 2 J/cm2 of UV-A), whereas with MMNL chemotaxis was inhibited at 1 microgram/ml of 8-MOP plus 2 J/cm2 of UV-A and lymphocyte proliferation was diminished at 0.1 microgram/ml plus 0.1 J/cm2. Since with the MMNL, as compared with the PMNL, a longer time period was present between PUVA exposure and analysis, and since no difference between these cell types in trypan blue exclusion could be seen, the relative sensitivity of the MMNL functions was taken as evidence of DNA damage being a mechanism for the observed PUVA-induced effects.
Insights
Photochemotherapy (PUVA) affects immune cells. Monomorphonuclear leukocytes (MMNL) showed reduced function at lower PUVA doses than polymorphonuclear leukocytes (PMNL), suggesting DNA damage in MMNL.
Area of Science:
- Immunology
- Photobiology
- Dermatology
Background:
- Photochemotherapy, specifically PUVA (psoralen plus UV-A), is a common treatment for skin conditions.
- The effects of PUVA on human immune cells, particularly leukocytes, require further elucidation.
Purpose of the Study:
- To investigate the in vitro effects of 8-methoxypsoralen (8-MOP) and UV-A radiation on human polymorphonuclear (PMNL) and monomorphonuclear leukocytes (MMNL).
- To assess the impact of PUVA on key immune functions including chemotaxis, bactericidal activity, and lymphocyte proliferation.
Main Methods:
- Human PMNL and MMNL were exposed to varying concentrations of 8-MOP and UV-A doses.
- Assessed immune cell functions: chemotaxis, bactericidal activity, and mitogen-stimulated proliferation.
- Evaluated cell viability using trypan blue exclusion.
Main Results:
- PMNL functions were depressed only at high PUVA doses.
- MMNL chemotaxis was inhibited at lower PUVA doses (1 microgram/ml 8-MOP + 2 J/cm2 UV-A).
- Lymphocyte proliferation in MMNL was diminished at even lower doses (0.1 microgram/ml 8-MOP + 0.1 J/cm2 UV-A).
Conclusions:
- MMNL are more sensitive to PUVA-induced functional impairment than PMNL.
- The differential sensitivity suggests DNA damage as a primary mechanism for PUVA effects on MMNL.
- Findings highlight the potential immunomodulatory effects of PUVA on specific leukocyte populations.