Distinct impact of malignancy and allergy on the clinical and immunological features of IgG4-related disease.

OBJECTIVES: To clarify the clinical and immunological characteristics of IgG4-RD based on the underlying diseases. METHODS: Consecutive patients with IgG4-RD treated at Keio University Hospital between 2010 and 2021 were divided according to the presence of malignancy or allergy into three groups. The clinical characteristics and 56 immune cell subsets in the peripheral blood were compared among the groups. RESULTS: Among 123 patients, 18 (14.6%) had malignancy including 4 with allergy (malignancy group), 57 (46.3%) had allergy alone (allergy group), and 48 (39.0%) had neither (idiopathic group). In the malignancy group, the patients were older (70.1 vs. 54.4 vs. 64.9 years, p<0.001), male-dominant (83.3 vs. 42.1 vs. 54.2%, p=0.008), and had smoking habits (77.8 vs. 42.1 vs. 43.8%, p=0.02). They also had significant involvement of the aorta/large vessels (33.3 vs. 7.0 vs. 20.8%, p=0.02), while the patients in the allergy group tended to have orbital/lacrimal gland involvement. Remission and relapse rates were not different between the groups; however, overall survival was significantly poorer in the malignancy group (p=0.02). Comprehensive immunophenotyping of the peripheral blood revealed that the increase in CXCR5+CD2-double negative T cells and the decrease in naive CD8 T cells were characteristic of the malignancy group. CONCLUSIONS: The clinical and immunological phenotypes of IgG4-RD differ among those with underlying diseases.

Anti-glomerular basement membrane diseases and thrombotic microangiopathy treated with rituximab.

A 68-year-old male patient presented with a 2-week history of malaise and anuria. Renal replacement therapy with haemodialysis was begun for acute kidney injury. His anti-glomerular basement membrane (anti-GBM) antibody titre was 3060 U/ml. Based on this finding, anti-GBM disease was diagnosed. Plasmapheresis and high-dose glucocorticoid therapy were begun, but his haemolytic anaemia and thrombocytopenia progressed. A disintegrin and metalloprotease with thrombospondin type 1 motif, 13 (ADAMTS-13) activity decreased to 33%, but no inhibitor was detected. Secondary thrombotic microangiopathy was suspected, and rituximab therapy was begun. The addition of rituximab is thought to have further reduced the anti-GBM antibodies, prevented recurrence, stabilised the platelet count, and facilitated the patient's withdrawal from plasmapheresis and glucocorticoid therapy. Rituximab may be a viable therapeutic option for anti-GBM diseases complicated with thrombotic microangiopathy.

Diagnosing Pollen-food Allergy Syndrome Allergologically in a Patient with Suspected Eosinophilic Gastroenteritis.

Pollen-food allergy syndrome (PFAS) consists of type I allergy to pollen and multiple food items that are cross-reactive to the pollen. PFAS typically occurs in the oral cavity and can co-occur with eosinophilic esophagitis. However, it is infrequently reported to present with symptoms of eosinophilic gastroenteritis (EGE), such as abdominal pain and eosinophilic infiltration of the gastrointestinal tract. We herein report a patient with a condition initially suspected of being EGE based on symptoms and pathological findings that was later diagnosed as PFAS associated with birch pollen. PFAS should be considered as a differential diagnosis in patients with EGE-like symptoms.