Nickel-induced proliferation of both memory and naive T cells in patch test-negative individuals.

Lymphocyte transformation test has often been used as an in vitro test for nickel allergy. We have previously demonstrated the presence of nickel-reactive T cells in individuals with no history of allergic disease and with a negative patch test towards NiSO4. In this study, we show that this proliferative response was mainly confined to T cells within the CD4+ subset. In contrast to conventional recall antigens such as tetanus toxoid, in vitro stimulation using NiSO4 activated both FACS-purified CD4+CD45RA+ 'naive' and CD4+CD45RO+ 'memory' T cells. To determine which cell population reacted with nickel to induce T cell activation, peripheral blood mononuclear cells were separated into macrophages and non-adherent, HLA-DR-depleted T cells. We found that preincubation of monocytes/macrophages but not T cells with NiSO4 resulted in subsequent T cell proliferation. This result demonstrated that nickel did not exhibit any direct effect on the T cell. Furthermore, the NiSO4-induced T cell proliferation could be blocked by antibodies towards MHC class II (HLA-DR) molecules. Our results substantiate the concept that individuals with a negative patch test towards NiSO4 contain in their peripheral blood T cells capable of recognizing nickel or nickel-modified peptides. In contrast to conventional recall antigens, both memory and naive T cells were activated. Thus, when compared with data obtained from nickel-allergic individuals, this study shows a comparable nickel-inducible T cell activation in non-allergic individuals.

[Acanthamoeba, Naegleria and invertebrates in wet areas of physiotherapy equipment in hospitals]. / Acanthamoeben, Naeglerien und Invertebraten in Feuchtbereichen von Physiotherapieeinrichtungen in Krankenhäusern.

In the course of investigations on the occurrence of primary free-living amoebae in different aquatic habitats, especially Naegleria and Acanthamoeba, we now investigated the moist areas in physiotherapeutic departments of 10 hospitals. As a result 61% of the swabs taken in those areas were positive with one or several species of amoebae cultivated on NN-agar according to Page. Among many other species observed during this study we were able to isolate 47 strains of Acanthamoeba and only two strains of Naegleria. The Naegleria-strains did not appear to be thermophilic. Therefore they are part of the N. gruberi-complex, which is considered to include only non pathogenic strains. Six from 47 strains of Acanthamoebae isolated revealed pathogenic characters as demonstrated in the MIT (Mice inoculation test). As a remarkable result four of these 6 strains with proven pathogenicity were not thermophilic at + 40 degrees C. Eventually all strains even not being thermophilic should in future be tested on pathogenicity. Additionally, nematodes and rotifers were isolated from several samples.