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The construction of an in vitro model allowed an investigation of the basic functions of immunocompetent cells after laser irradiation. Among low-energy laser sources, the helium-neon (He-Ne) laser, with a wavelength of 632.8 nm, has often been found to produce photobiological effects including evidence of interference with immunological functions. Previous experiments revealed an influence of He-Ne laser irradiation on concentrations of interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2), and interferon-gamma (IFN-gamma) in supernatants of cultures of human peripheral blood mononuclear cells (PBMC) with increased cytokine concentrations after irradiation of 18.9 J/cm2 and decreased concentrations after irradiation of 37.8 J/cm2. Now, the mechanisms involved were studied. Results showed that cytokine production of cells stimulated with phytohemagglutinin (PHA), concanavalin A (Con A), or bacterial lipopolysaccharide (LPS) was altered significantly after laser irradiation but not after stimulation with staphylococcus aureus enterotoxin B (SEB). In situ hybridization of IFN-gamma mRNA producing PBMC revealed that the number of positive cells was modulated similarly. The results were identical in cultures of enriched monocytes (M phi) or enriched T cells. Cells of the human monocytic cell line Mono Mac 6 were also influenced after LPS stimulation, whereas constitutively IL-2-producing Jurkat cells were not influenced by laser irradiation at any energy density. Analysis of the IL-2 receptor (IL-2R) and intercellular adhesion molecule-1 (ICAM-1) expression in PBMC showed partial down-regulation of both receptors at 37.8 J/cm2, but only after stimulation with PHA.(ABSTRACT TRUNCATED AT 250 WORDS)

Several lines of evidence have supported the role of immunological mechanisms in the pathogenesis of multiple sclerosis (MS) and new immunomodulatory strategies for its treatment, e.g. subcutaneous application of interferon (IFN)-beta, have emerged. We investigated the ability of peripheral blood mononuclear cells (PBMC) in 21 consecutive patients with clinically definite MS to produce interferons and lymphokines in response to viral or mitogenic stimulation. Ten patients showed clinical signs of disease activity (acute relapse) and 11 patients were in a stable condition. Additionally, white blood count, leukocyte differentiation and lymphocyte subtyping were performed. A group of age-related healthy blood donors served as control (n=20). There was no difference between patients and controls in the production of IFN-gamma, tumor necrosis factor (TNF)-alpha and soluble interleukin (IL)-2 receptor. IFN-alpha and IFN-beta responsiveness, however, was significantly lower in patients with stable disease than in patients with active disease and controls (p<0.001). Furthermore, secretion of IL-2 after stimulation was significantly diminished in both patient groups as compared to the control group (p<0.01). Analysis of T-cell subsets revealed a significantly lower amount of CD8+ T-cells in patients with stable disease, leading to a significantly higher CD4/CD8 ratio in this group as compared to patients with active disease. Our study depicted an IL-2 deficiency in MS patients which is shared with other autoimmune diseases. In addition, our findings suggest that the ability to produce type-I IFNs, IFN-alpha and IFN-beta, is primarily impaired in MS patients and changes in correlation to the course of disease activity.

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