Polymorphic eruption of pregnancy and herpes gestationis: comparison of granulated cell proteins in tissue and serum

Polymorphic eruption of pregnancy (PEP) and herpes gestationis (HG) are pre gnancy-related dermatoses of unknown aetiology with eosinophil infiltration which, at early stages, may show similar clinical and histopathological fe atures. To determine the relative contributions of eosinophils, neutrophils and mast cells to the pathogenesis of PEP and HG through deposition of gra nule proteins, we studied tissue and serum from 15 patients with PEP and 10 with HG, Using indirect immunofluorescence with antibodies to human eosino phil granule major basic protein (MBP), eosinophil-derived neurotoxin (EDN) , eosinophil cationic protein (ECP), neutrophil elastase and mast cell tryp tase, we determined and compared cellular and extracellular staining patter ns in lesional skin biopsy specimens and, using immunoassay, measured MBP, EDN, and ECP in patients' sera, Eosinophil infiltration and extracellular p rotein deposition of all three eosinophil granule proteins were present in both PEP and HG indicating a pathogenic role for eosinophils in both diseas es, Staining for eosinophil granule proteins was especially prominent in ur ticarial lesions and around blisters in HG. EDN and ECP serum levels in PEP and ECP serum levels in HG were significantly increased compared with thos e in normal pregnant and normal nonpregnant serum. Neutrophils were more pr ominent in HG specimens than in PEP specimens; extracellular neutrophil ela stase was minimally present and similar in both diseases. Mast cell numbers and extracellular tryptase deposition did not differ between the two disea ses and did not differ from mast cell counts in skin of normal pregnant wom en. This study shows that eosinophil granule proteins are deposited extrace llularly in tissue and are increased in serum in both PEP and HG. Moreover, eosinophil involvement in the two diseases is more consistent than neutrop hil and mast cell involvement. Comparatively, tissue eosinophil infiltratio n and extracellular protein deposition is more extensive in HG than in PEP, suggesting that eosinophil involvement is greater in the pathogenesis of H G than PEP and similar to that found in bullous pemphigoid.