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Updated: Sep 25, 2026
Studying Chronic Exposure of Mice to Ultraviolet B Radiation
Published on: August 19, 2025
The effects of ultraviolet B treatment on the expression of adhesion molecules by circulating T lymphocytes in
H Sigmundsdottir1, J E Gudjonsson, H Valdimarsson
1Department of Immunology, Landspitali University Hospital, 101 Reykjavik, Iceland.
Background:
T lymphocytes are believed to play a role in the pathogenesis of psoriasis; > 80% of T lymphocytes that infiltrate psoriatic lesions express the surface glycoprotein cutaneous lymphocyte-associated antigen (CLA), compared with < 20% in the blood. Exposure to ultraviolet (UV) B is an effective treatment for psoriasis.
Objectives:
To compare the effects of UVB treatment of psoriasis on the expression of CLA and several other surface markers expressed by circulating T lymphocytes.
Methods:
Peripheral blood mononuclear cells from psoriatic patients were stained for adhesion molecules and stimulated with streptococcal antigens before and once weekly during 3 weeks of UVB treatment.
Results:
A marked and progressive decrease was observed during the treatment in expression of the CLA and the very late antigen-4alpha by T cells; this decrease correlated closely with clinical improvement (Psoriasis Area and Severity Index). T-cell expression of intercellular adhesion molecule-1 was not significantly affected during the treatment and no change was observed in the activation markers CD25 and CD69 or lymphocyte proliferation after stimulation with streptococcal antigens or superantigens.
Conclusions:
UVB treatment is associated with a marked reduction in the expression of skin-homing molecules by circulating T cells. This may be relevant to the therapeutic effect of UVB in psoriasis.
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