Immunologic analysis of patients with postinfectious bronchiolitis obliterans

Purpose:This study aimed to analyze the immunologic profile of children with postinfectious bronchiolitis obliterans (PIBO) in order to approach pathophysiology affected by host factors. Methods: A total of 10 children with PIBO were prospectively enrolled. We obtained information on demographics from their caregiver and electric medical records. Peripheral blood samples were collected before cyclic systemic methylprednisolone therapy and complete blood count, immunoglobulin level and lymphocyte subset were analyzed. Results:The white blood cell count and immunoglobulin level were within the normal range in children with PIBO.The CD4+/CD8+ ratio was not significantly different from those of the healthy control group. A decreased proportion of both central memory T cells (median [interquartile range]; 135% [8.3%-16.3%] vs. 185% [15.9%-24.1 degrees/0], P= 0.01) and effector memory T cells (10.3% [5.0%-18.4%] vs. 20.9% [16.6%-26.3%], P= 0.03) in CD4+T cells was observed in the PIBO group compared with those in the control group. In CD8+T cells, the proportion of effector memory T cells (7.8% [4.2%-13.8%] vs. 24.3% [15.3%-27.9%], P= 0.02) and CD45RA+effector memory T cells (16.2% [11.0%-36.6%] vs. 24.2% [17.1%-39.7%], P= 0.04) was decreased in the patient group compared with the control group. Conclusion: It is suggested that T lymphocyte subset abnormalities may be associated with a decrease in the ability to differentiate the T cells immediately upon reinfection and induce an effective response to infection. These results may partially explain the pathophysiological individual vulnerabilities to PIBO after lower respiratory tract infections in children.