Examination of tetrachlorosalicylanilide (TCSA) photoallergy using in vitro photohapten-modified Langerhans cell-enriched epidermal cells.

Lymphocytes from BALB/c mice photosensitized in vivo to tetrachlorosalicylanilide (TCSA) were investigated to determine whether they could be stimulated to proliferate when cultured with Langerhans cell-enriched cultured epidermal cells (LC-EC) photohapten-modified in vitro with TCSA + UVA radiation. Cultured LC-EC were photohapten-modified in vitro by irradiation in TCSA-containing medium using a 1000-watt solar simulator equipped with filters to deliver primarily UVA radiation (320-400 nm). Lymphocytes from TCSA-photosensitized mice were incubated with LC-EC that had been treated in vitro with 0.1 mM TCSA and 2 J/cm2 UVA radiation (TCSA + UVA). Responder lymphocytes demonstrated a significant increase in their blastogenesis response compared to lymphocytes that were incubated with LC-EC irradiated with UVA prior to treatment with TCSA (UVA/TCSA) or with LC-EC that had received no treatment. Lymphocytes from naive mice or mice photosensitized with musk ambrette (MA) demonstrated a significantly lower response to LC-EC modified with TCSA + UVA, indicating the specificity of the response. Maximum blastogenesis response was achieved when LC-EC were treated with 0.1 mM TCSA and a UVA radiation dose of at least 0.5 J/cm2. Epidermal cells depleted of LC by treatment with anti-Ia antibody plus complement or by an adherence procedure were unable to stimulate this blastogenesis response. Epidermal cells treated in vitro with TCSA + UVA demonstrated enhanced fluorescence compared to control cells. The fluorescence observed was not restricted to any specific epidermal cell type; however, fluorescence microscopy studies revealed that dendritic Ia-positive cells, presumably LC, were also TCSA fluorescent. Flow cytometry showed that Ia-positive epidermal cells demonstrated the greatest UV fluorescence when treated with TCSA + UVA compared to both cells irradiated with UVA and subsequently treated with TCSA and untreated cells. This is consistent with the enhanced antigen presentation capability of TCSA + UVA treated LC-EC, which leads to the conclusion that LC photohapten-modified in vitro with TCSA + UVA demonstrate enhanced TCSA fluorescence and are capable of stimulating lymphocytes from TCSA photosensitized mice in an antigen-specific manner.

Increased hyaline droplet formation in male rats exposed to decalin is dependent on the presence of alpha 2u-globulin.

A peculiar decalin-induced male rat nephropathy associated with the altered renal handling of filtered protein appears limited to the accumulation of the protein, alpha 2u-globulin. Several strains of male rats that produce alpha 2u-globulin (Fischer-344, Sprague-Dawley, Buffalo, and Norway Brown) demonstrate spontaneous renal cortical hyaline droplets which are exacerbated after exposure to decalin. In all cases, a close correlation exists between hyaline droplet formation observed histologically and alpha 2u-globulin accumulation measured biochemically. In stark contrast, the NCI-Black-Reiter strain, which does not produce measurable quantities of alpha 2u-globulin, neither forms hyaline droplets nor accumulates any filtered protein in its kidney cortex either spontaneously or after exposure to decalin. Also, female rats injected ip with male rat alpha 2u-globulin exhibit increased hyaline droplet formation and alpha 2u-globulin accumulation when treated with decalin. These data provide evidence that the presence of alpha 2u-globulin is key in understanding why this nephropathy appears unique to the male rat.