Biological therapies for Crohn’s disease (CD), including infliximab, adalimumab, and vedolizumab, show variable efficacy. While some predictive biomarkers exist, data on regulatory immune cells are limited. This study examined whether baseline levels of circulating T and B cell subsets can predict response to these treatments. We recruited 43 adults with conventional treatment-resistant active CD (CDAI > 330) and 16 healthy controls. Blood samples were analysed by flow cytometry at baseline (week 0) and after induction therapy (week 12 or 14, depending on the received drug) to measure T and B cell subsets and correlate them with disease activity. CD patients at baseline showed a significantly reduced frequency of memory B cells, CD5⁺CD1d⁺ B cells, plasmablasts, and transitional B cells. Additionally, significant negative correlations were identified between transitional B cells and calprotectin/platelets, and between CD5⁺CD1d⁺ B cells and calprotectin. All CD patients responded clinically to biologic therapy. In those treated with infliximab or adalimumab, mature naïve B cells decreased, with a trend toward increased CD24^hiCD27⁺ B cells. Adalimumab responders showed a trend toward higher CD161 expression on Tregs, while vedolizumab-treated patients had a slight increase in plasmablasts. Biologic therapies in CD revealed treatment-specific immune correlations: infliximab/adalimumab responses involved B and T cell changes linked to inflammation, while VDZ response correlated with CD4⁺ and CD5⁺CD1d⁺ B cells. Our study suggests that infliximab/adalimumab induction therapy in CD expands circulating CD24^hiCD27⁺ B cells and reduces mature naïve B cells, while vedolizumab increases plasmablasts. These B-cell changes may reflect distinct mechanisms and serve as potential response biomarkers.

BACKGROUND Diffuse large B-cell lymphoma (DLBCL) is the most common form of malignant lymphoma. The hypothesis that age-related immune decline plays a role in the development of lymphoma is well established and exemplified by the association between Epstein-Barr virus (EBV) and DLBCL. This report describes a 22-year-old liver transplant patient with ulcerative colitis (UC) presenting with ileus and diffuse large B-cell lymphoma (DLBCL). Because of the symptoms, an exacerbation of UC was initially suggested, which contributed to a delay in definitive diagnosis. CASE REPORT A 22-year-old patient with a medical history of ulcerative colitis, liver transplantation, and use of immunosuppressive drugs presented gradually progressive abdominal pain, bloating, and, eventually, lack of bowel movements. Initially, abdominal X-ray revealed the presence of radiological features consistent with sub-ileus/ileus. Then, the serological tests for EBV in the IgG class yielded positive results. Subsequently, the contrast-enhanced abdominal and pelvic computed tomography (CT) scans revealed the presence of enlarged lymph nodes forming a conglomerate. A percutaneous thick-needle biopsy of a conglomerate of lymph nodes in the abdominal cavity was performed, which revealed DLBCL. After diagnosis, the patient underwent 6 cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy, achieving remission. CONCLUSIONS This case report emphasizes that clinicians need to consider the risk of oncogenesis associated with the prolonged use of immunosuppressive agents and EBV-seropositive infection status. Screening for EBV before initiating immunosuppressive therapy should be compulsory. EBV-negative patients on immunosuppression must especially avoid EBV infection, while EBV-positive patients must be monitored more closely due to higher oncological risk.