Arachidonic acid and prostanoids in suction blister fluid from psoriatic lesions and unaffected skin

A new reliable chemiluminescence immunoassay (CLIA) for prostaglandin E2 using enhanced luminol as substrate

A sensitive and reliable chemiluminescence immunoassay suitable for the quantitative determination of prostaglandin E2 (PGE2) has been developed using 96 well microtiter plates (MTP). The assay is based on a competitive reaction between a highly specific monoclonal anti-PGE2 antibody (mouse), free antigen and solid phase bound antigen. The MTP was first coated with a bovine serum albumin (BSA)-PGE2 conjugate. Then, after preincubating, the anti-PGE2 antibody (Ab) and the analyte were added. The remaining amount of free antibody was captured by the solid phase bound BSA-PGE2 conjugate. The monoclonal antibody captured on the MTP was determined using biotinylated anti-mouse-Ab and a complex of avidin and biotin-labelled horseradish peroxidase (HRP). Substrate for HRP was the cyclic diacyl hydrazide compound luminol, enhanced by p-iodophenol. Photons emitted during the reaction were measured using a photomultiplier tube. The assay has been validated with assay buffer and human plasma over a concentration range of 10-50,000 pg/ml. The lower limit of quantification is 100 pg/ml (2 pg/well) and 150 pg/ml (3 pg/well) for buffer and plasma, respectively. The intra-day coefficients of variation (CV) for the range of 100-50,000 pg/ml are 3.2-8.9% (buffer) and 4.2-17.7% (plasma) and inter-day CV are 2.9-19.8% (buffer) and 3.6-21.2% (plasma). The method can be used for quantification of PGE2 in biological fluids like plasma and suction blister fluid.

High levels of hyaluronate in suction blister fluid from active psoriatic lesions

Hyaluronate concentrations were measured in suction blister fluid from blisters raised on the abdominal skin of 12 healthy control subjects, on unaffected skin of 14 patients with psoriasis, and on lesional skin from 12 of these patients. The concentrations of hyaluronate in blister fluid from the controls and from the uninvolved skin of patients with psoriasis were within the same range (2.9-10.5 and 2.4-7.8 mg/l, respectively). Six of the patients had active, widespread, untreated psoriasis and in these cases the hyaluronate concentration in blister fluid from lesional skin was greatly increased (24-30 mg/l). Patients with stable or regressing psoriasis had no significant increase in hyaluronate levels in the blister fluid from lesional skin compared with the controls (range 4.6-12.4 mg/l). Patients with active psoriasis had significantly higher serum hyaluronate concentrations than the controls and those with inactive psoriasis.

Topical application of nonsteroidal anti-inflammatory drugs prevents vehicle-induced improvement of psoriasis

In a double-blind fashion, we compared the effect of topical application of 1% indomethacin cream or 1% meclofenamate cream with the effect of vehicle therapy alone in thirty patients with psoriasis. After 4 weeks' treatment of bilaterally symmetric psoriatic plaques, the indomethacin-treated sides were worse than the vehicle-treated sides in fourteen of twenty patients (p less than 0.01); the meclofenamate-treated sides were worse than the vehicle-treated sides in seven of ten patients (p less than 0.05). We suspect that the nonsteroidal anti-inflammatory drugs contributed to the maintenance of our patients' psoriasis by altering the arachidonic acid transformation cascade.

Circulating hyaluronate in psoriasis

A radioassay method allowing measurements of low concentrations of circulating hyaluronate was used in a study of serum hyaluronate concentrations in 44 patients with psoriasis. Twenty-three of them had only skin lesions and 21 had both skin lesions and arthropathy. In both of these groups significantly elevated serum levels of hyaluronate were found. The highest values were observed in those with widespread and active skin disease and/or active arthritis. Serum hyaluronate positively correlated with the plasma concentrations of alpha 1-antitrypsin and haptoglobin and also with ESR, which may indicate a relationship between acute inflammation and increased production of hyaluronate. Seven patients with widespread atopic dermatitis included for comparison had normal hyaluronate values. In blister fluid from lesional skin in two patients with acute psoriasis, very high concentrations of hyaluronate were found, in comparison with the concentrations in blister fluid from non-involved skin. The increased concentration of serum hyaluronate in psoriasis indicates involvement of dermal and synovial tissue in psoriasis, in addition to the epidermal changes.