Israel Medical Association Journal

Background: Group A Streptococcus (GAS) causes a wide spectrum of acute infections and immune-related diseases, most of which include a dermatological presentation. However, dermatological findings have a wide range of other possible etiologies. The diagnosis of GAS-related disease requires an indication of preceding GAS infection by direct culture or by measuring antistreptolysin O (ASLO) titer.

Objectives: To explore the correlation between ASLO positivity and dermatological diseases.

Methods: We analyzed clinical data from all cases of patients over 18 years of age who underwent ASLO testing between the years 2016 and 2020 in the Department of Dermatology at Rambam Health Care Campus.

Results: Of 152 adult patients with ASLO tests, 100 had diagnoses that were potentially related to streptococcal infection. Vasculitis and psoriasis were the most suspected diagnoses. Positive ASLO test was found in 44 (29%) patients. The diagnoses showing the highest ratio of positive ASLO were psoriasis (60%), erythema nodosum (46%), skin infections (43%), Sweet syndrome (33%), and vasculitis (15%). Psoriasis types included plaque psoriasis (8 patients), guttate psoriasis (3 patients), and palmoplantar pustulosis and erythroderma (2 patients each).

Conclusions: Although the applicability of ASLO for the spectrum of dermatological diseases remains unclear, our results enhance the practical relevance of the test. We showed a higher prevalence of positive ASLO tests in psoriasis and erythema nodosum cases and a lower prevalence in vasculitis. Notably, ASLO was positive in all psoriasis subtypes, suggesting high utility of the test for psoriasis.

Objectives: To determine the properties of HAM as an antigenic substrate for the detection of autoantibodies in pemphigus vulgaris and bullous pemphigoid.

Methods: Immunomapping and tandem liquid chromatography mass spectrometry were used to delineate the antigenic structure of HAM in 25 pemphigus patients, 41 pemphigoid patients, and 36 controls. Immunoblotting and indirect immunofluorescence were used to study the diagnostic utility of HAM, and the results were compared to those of indirect immunofluorescence on monkey esophagus, immunoblotting using normal human skin, and enzyme-linked immunosorbent assay (ELISA).

Results: Immunomapping demonstrated the presence of all the antigens known to be targeted in autoimmune bullous skin diseases, in both normal human skin and HAM, except for the absence of BP230, and low threshold levels of Dsg1, Dsg3 and Dsc3 in HAM. HAM indirect immunofluorescence demonstrated anti-basement membrane zone antibodies in 48.7% of the pemphigoid patients, and anti-intercellular space antibodies in 72.0% of the pemphigus patients. HAM immunoblotting did not demonstrate anti-BP230 antibodies, but detected anti-BP180 antibodies in 53.6% of the pemphigoid patients. It did not demonstrate anti-Dsg1 and/or anti-Dsg3 antibodies in any of the pemphigus patients. These results were inferior to those of ELISA and monkey esophagus indirect immunofluorescence.

Conclusions: Compared to other studied methods, HAM does not offer advantages in detecting autoantibodies in bullous pemphigoid and pemphigus vulgaris.