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P426 Lympocytosis in patients with inflammatory bowel disease treated with anti-TNFa agents: is it significant?

K. Soufleris*1, N. Kafalis1, M. Charalampidis1, K. Fasoulas1, I. Pilpilidis1, G. Lazaraki1, D. Tzilves1, D. Markala2

1Theagenion CHT, Gastroenterology Department, Thessaloniki, Greece, 2Theagenion CHT, Dir Haematology Lab, Thessaloniki, Greece

Background

True lymphocytosis has been sporadically reported to occur in rheumatology patients treated with anti-TNFa agents. Although it is generally considered as a benign, reactive and reversible phenomenon there is concern of a possible association with malignant lymphoproliferative disorders. Anti-TNFa-based immunosuppressive therapy has been implicated as a causal agent in patients with autoimmune diseases. Higher doses and combination with azathioprine in patients with inflammatory bowel diseases compared with other rheumatology patients could impact lymphocyte expansion more profoundly.

Methods

We evaluated peripheral blood lymphocyte levels in all IBD patients who initiated anti-TNF therapy in the outpatient IBD clinic during the last 3 years, with no evidence of lymphocytosis for at least 3 months prior to initiation of therapy. Lymphocytosis was defined as a lymphocyte count greater than 4000 per microlitre. In patients with lympocytosis peripheral blood T, B, and NK lymphocyte subpopulations were analysed using flow cytometry and lymphocyte levels were followed up for at least 6 months. We investigated possible associations with disease and patient characteristics, treatment, outcome and safety.

Results

We included a total of 62 patients: mean age 38.4 years, 30 males, 47 with Crohn’s disease, 15 with ulcerative colitis, 27 on Infliximab, 35 on adalimumab, 2 on golimumab, 14 on combination with azathioprine. Lymphocytosis was observed in 16 patients (26.8%). Lymphocytosis significantly correlated with administration of infliximab: OR 5.02 (95% CI 1.2–17), p = 0.01, and combination therapy with azathioprine: OR 4.3 (95% CI 1.2–15.4), p = 0.024. Patients with lymphocytosis showed better treatment response: 15/16 (93.7%) vs. 28/46 (60.8%), p = 0.014. No difference in serious adverse events (infections, malignancies) was observed over a mean follow-up duration of 27.31 (22.2–32.3) months. Treatment interruptions and de-escalations led to disappearance and lesser degrees of lymphocytosis, respectively.

Conclusion

Lymphocytosis was observed in one-fourth of our cohort of IBD patients commenced on anti TNF-therapy. It was polyclonal, reversible, and dose related. It correlated with administration of infliximab and combination therapy with azathioprine. Patients with lymphocytosis were more likely to respond to therapy. Short-term safety was similar but long-term clinical significance remains unknown and should be further studied.