Natural killer (NK) cell activity and NK-related cell surface markers in patients with atopic dermatitis

Perforin hyperreleasability and depletion in cytotoxic T cells from patients with exacerbated atopic dermatitis and asymptomatic rhinoconjunctivitis allergica

BACKGROUND

As a plasma membrane pore-forming protein, perforin is essential for T-cell cytotoxicity mediated by lytic granules. Recent studies on the immune system of perforin knockout mice demonstrated striking similarities to the immunopathology of atopic diseases.

OBJECTIVE

We sought to investigate the perforin system of atopic patients.

METHODS

Monoclonal antibodies were used to characterize perforin-positive PBMCs of patients with exacerbated atopic dermatitis (AD) and asymptomatic rhinoconjunctivitis allergica (RCA) by means of immunoflow cytometry. In addition, a perforin release assay was developed to quantify the velocity of ionomycin and phorbol 12-myristate 13-acetate-induced secretion of lytic granules.

RESULTS

In atopic patients significantly fewer lymphocytes contained perforin-positive lytic granules compared with those of healthy control subjects (patients with AD: 14% +/- 5%, n = 13, P <.0001; patients with RCA: 24% +/- 5%, n = 9, P <.01; healthy control subjects: 33% +/- 11%, n = 13). Of all CD8(hi+) cytotoxic T lymphocytes (CTLs), only 18% +/- 9% and 17% +/- 12% were perforin-positive in patients with AD and RCA, respectively, compared with 44% +/- 13% in control subjects (P <.0001). In addition, perforin-positive CD8(hi+) CTLs of atopic patients released their perforin twice as fast and more completely than control CTLs. This means that 50% of initially perforin-positive CD8(hi+) CTLs from patients with AD and RCA released their perforin completely within 32 +/- 16 and 36 +/- 19 minutes, respectively, and an over 85% release was reached within 113 +/- 41 and 118 +/- 60 minutes, respectively. In CTLs of healthy control subjects, however, it took 64 +/- 40 minutes to achieve a 50% release of lytic granules, and an 85% depletion was not reached in 60% of healthy control subjects, even after 180 minutes.

CONCLUSION

The perforin hyperreleasability explains, at least in part, the decreased percentage of perforin-positive CD8(hi+) CTLs in atopic patients. These distortions in the system of lytic granules of atopic patients may contribute to the functional defects observed in T-cell cytotoxicity in vivo and in vitro in patients with AD and RCA.

Reduced IL-12 level correlates with decreased IFN-gamma secreting T cells but not natural killer cell activity in asthmatic children

BACKGROUND

Accessory cells such as macrophages and natural killer cells, and their cytokines such as IL-10, IL-12, and IFN-gamma have been suggested to play a critical role in the development of T helper cells.

OBJECTIVE

Both natural killer cells and peripheral blood mononuclear cells were isolated and stimulated for their ability in producing cytokines. In addition, the percentage of IFN-gamma-secreting cells was analyzed with the method of intracellular staining.

RESULTS

The data suggested (1) no significant difference between asthmatic children and normal controls in number, cytotoxicity, and IFN-gamma production of purified NK cells; (2) decreased secretion of IL-12 by stimulated peripheral blood mononuclear cells in asthmatic children compared with normals (P < .05); (3) decreased production of IFN-gamma by PBMC from asthmatic children compared with normals (P < .05); and (4) intracellular expressed IFN-gamma level was lower in CD4+ T cells of asthmatic children (P < .05).

CONCLUSION

The results suggested that IL-12 produced predominantly by macrophages and associated decreased IFN-gamma-secreting CD4+ T cells play a critical role in the pathogenesis of asthma.

Interleukin 2 therapy in severe atopic dermatitis

Interleukin 2 (IL-2) at a dose of 10,000 to 20,000 U/kg/q 8 hr was given for 9-12 days to six patients with cases of severe atopic dermatitis (AD) which were refractory to conventional therapy. After IL-2 therapy, the clinical symptoms and signs of eczema including pruritus, scratching, papulovesicles, and lichenification were much improved, but all of them recurred 2-6 weeks after stopping treatment. Adverse reactions were similar to those reported previously, but all of them subsided after discontinuation of therapy. Laboratory findings showed decreased T-cell subsets, especially CD4+ cells, and increased IL-2R+ (CD25) cells, but there was no significant change in serum IL-2, serum IgE, or in vitro IgE production. Immunopathological studies of the skin biopsies showed decreased mononuclear-cell infiltration, depletion of CD4+ cells, and enhanced expression of CD25 and HLA-DR antigens. As lymphokine-activated killer (LAK)-cell activity against cultured fibroblasts was similar in patients with AD and in normals and CD1+ Langerhans cells were not decreased after IL-2 therapy, we speculate that the depletion of helper/inducer CD4+ cells and hence abrogation of the exaggerated antigen processing and cellular activation in diseased skin are the explanation for the transient efficacy of IL-2 in the treatment of atopic dermatitis.