Chronic urticaria with sensitization to Anisakis simplex: Which factors contribute to detectable specific IgG4 values?

Abstract

61 Chronic Urticaria With Sensitization to Anisakis Simple~, Which Factors Contribute to Detectable Specific IgG4 Values? Francisco Vega de La Osada, Alvaro Daschner, Bego~a Gonzdlez Leza Hospital University La Princess, Madrid, Spain In our area a high proportion of patients with chronic urticaria are sensitized to Anisakis simplex (A.s.). In order to elucidate a possible diagnostic value for specific IgG4, patients with chronic urticaria and with measurable specific IgE values (>0,7 kU/1, Cap-FEIA, Pharmacia, Uppsala, Sweden) were divided into two groups: Group A was comprised of 23 patients with detectable specific IgG4 against A.s. and in group B 21 patients were included without detectable IgG4. Both groups were compared with respect to age, specific IgG against A.s. and duration of symptoms (mean values, standard deviation (SD), t-test) as well as for total and specific IgE against A.s. (median values, interquartile range (IQR) and Mann-Whitney). Spearman correlation coefficients were calculated between the mentioned parameters. Chi-square-test was used to compare the prevalence of Helicobacter-pylori infection (positive breath test), anarnnestic data of rhinoconjunctivitis or asthma as well as the prevalence of a suspected previous history of acute gastro-allergic Anisakiasis (acute urticaria/angioedema, abdominal pain and or nausea after intake of raw or undercooked fish) in both groups. Mean age was 44,2 (SD 16,5) years in group A and 44,0 (SD 13,4) years in group B. IgG4 levels in group A ranged from 177-6405 (median 869) lag/l. Mean specific serum IgG was higher in group A than in group B (12,1, SD 10,5 mg/l versus 6,7, SD 4,0 mg/1; p=0,05). Mean duration of symptoms did not differ in group A (20,4, SD 28,3 months) compared to group B (27,2, SD 33,7 months). Total IgE was higher in group A than in group B (median 241, IQR 125-382 kU/1 versus 149, IQR 82-192 kU/1, p=0,02). Also specific IgE was higher in group A (29,8, IQR 14-53 versus 4,5, IQR 1,5-14,4; p=0,001). If all patients were studied, IgG4 values correlated with total IgE (Rho 0,35; p=0,02), specific IgE (Rho 0,49; p=0,001 ) and specific IgG (Rho 0,51; p<0,001 ). If only those of group A were studied only specific IgG was correlated with specific IgG4 (Rho 0,71; p=<0,001). Seven of eight patients with suspected previous gastro-allergic Anisakiasis displayed detectable specific IgG4, compared to 12 of 27 patients who did not remember any previous fish-related symptoms (p= 0,032). Helicobacter-pylori infection or rhinoconjunctivitis/asthma did not significantly predispose the patients to belong to one of both groups. Some patients with acute urticaria/angioedema in the context of gastro-allergic Anisakiasis develop chronic urticaria, maintaining detectable specific IgG4 against A.s. However specific IgG4 levels are to be interpreted taking into account the levels of total IgE, specific IgE and specific IgG. Of these parameters, specific IgG seems to be more relevant, thus further studies should focus on other factors that influence specific IgG.