Arachidonic acid transformation is not stimulated in delayed pressure urticaria

The definition and diagnostic testing of physical and cholinergic urticarias--EAACI/GA2LEN/EDF/UNEV consensus panel recommendations

The recommendations for the definition and diagnosis presented in this position paper are the result of a panel consensus meeting held in December 2008 in Berlin. This consensus meeting was a joint initiative of EAACI (European Academy of Allergology and Clinical Immunology) Dermatology Section, the EU-funded network of excellence, GA(2)LEN (Global Allergy and Asthma European Network), the EDF (European Dermatology Forum) and UNEV (urticaria network e.V.). The aim of these recommendations is to improve the diagnosis and management of patients with physical urticaria or cholinergic urticaria and to promote research and a better understanding of these diseases. Our recommendations used the paper produced by a 1996 expert meeting (1) and they acknowledge the latest changes in our understanding of physical urticarias and cholinergic urticaria as well as the recent development of novel diagnostic tools. In addition, this consensus paper highlights areas of need for further research.

Delayed pressure urticaria

Delayed pressure urticaria is a mechanical urticaria in which pressure causes whealing. Delayed cutaneous erythema and edema occur in association with marked subcutaneous swelling after the application of a sustained pressure stimulus to the skin. The earliest reports and theories of the pathogenesis of delayed pressure urticaria are summarized. Detailed attention is given to making the diagnosis by taking a history and provoking the lesions. The clinical features and natural history are considered. The effects of the disorder on quality of life are delineated, and management strategies are suggested.

Chronic urticaria

Chronic urticaria remains a major problem in terms of etiology, investigation, and management. It is important to identify patients in whom physical urticaria is the principal cause of disability. Once confirmed by appropriate challenge testing, no further investigation is required. Urticarial vasculitis (UV) is a major differential diagnosis of "idiopathic" urticaria (CIU). I perform biopsy of most patients in this category because UV cannot be considered confirmed in the absence of histologic evidence. Patients with confirmed UV need to be thoroughly investigated for paraproteins, lupus erythematosus hepatitis B and C, and inflammatory bowel disease. Of patients with CIU, a few (<5%) prove to have food additive reactivity confirmed by placebo-controlled challenge testing. There is no convincing evidence of the involvement of Helicobacter pylori or parasite infestation as a cause of chronic urticaria, although H pylori could have an indirect role. Recently it has become clear that 27% to 50% of patients with CIU have functional autoantibodies directed against the alpha-chain of the high-affinity IgE receptor or less commonly against IgG. These antibodies, whose involvement has now been independently confirmed in several centers, are identified by autologous serum skin testing and confirmed by histamine release studies or immunoblotting. Their removal (by intravenous Ig or plasmapheresis) or treatment by cyclosporine has proved highly beneficial in severely affected patients. However, the routine treatment of all CIU patients, irrespective of etiology, remains the judicious use of H(1) antihistamines.

Increased interleukin 6, but reduced interleukin 1, in delayed pressure urticaria

Interleukin 1 (IL-1) and interleukin 6 (IL-6) were measured by bioassays in suction-blister exudates from lesional skin, from skin immediately following a pressure challenge, and from control skin (not subjected to pressure) of patients with delayed pressure urticaria. IL-6 activity in lesional exudates was significantly higher than in exudates from the other two sites. IL-1 activity in lesional exudates was not significantly higher than in the control exudates, but significantly less IL-1 activity was found immediately after pressure challenge than from the control site.

Inflammation of guinea pig dermis. Effects of leukotriene B4 receptor antagonist, SC-41930

Neutrophil (PMNL) infiltration is a prominent feature of human psoriasis. Psoriatic skin lesions contain abnormally high amounts of leukotriene B4 (LTB4), itself a potent PMNL chemoattractant both in vivo and in vitro. SC-41930 (7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)-propoxy]-3,4-dihydro-8- propyl-2H-1-benzopyran-2-carboxylic acid), an orally active LTB4 receptor antagonist, was tested topically in models of skin inflammation induced by 200 nmol of the calcium ionophore A23187 or 200 micrograms phorbol-12-myristate-13-acetate (PMA) applied topically to the guinea pig ear as assessed by ear weight, levels of the PMNL marker enzyme myeloperoxidase (MPO), and histological examination (PMA model) at 4 and 18 h respectively. When coapplied topically with A23187 or PMA, SC-41930 significantly inhibited epidermal inflammation with ED50 values of 0.6 and 4 mg, respectively. SC-41930 treatment also was associated with lowered dermal LTB4 levels in both models. The PMA-induced skin inflammation model also was assessed histologically and revealed acanthosis, edema, PMNL infiltration, and rete ridge prominence as long as 96 h after a single application that was completely inhibited by SC-41930 topical coapplication. Furthermore, oral treatment (40 mg/kg) significantly reduced edema and inflammatory cell infiltration in both models. These models possess many of the characteristics of human psoriasis, and agents such as SC-41930 that demonstrate activity in these models may well have therapeutic utility in the treatment of human psoriasis.