Immune Abnormalities in Patients With Single Ventricle Circulation Precede the Fontan Procedure

Background: Immune abnormalities are common in Fontan patients with protein-losing enteropathy. Limited data exist on immune function of other patients with single ventricle circulation. Methods: This prospective cohort study evaluated immunologic characteristics of children with single ventricle circulation from neonatal age up to early post-Fontan period. Results: Low leukocyte counts were observed in half of the patients prior to bidirectional Glenn and Fontan surgery. Total lymphocyte counts were below normal range in 36% to 63% of patients across all groups except patients following Fontan procedure who had normal counts. Typical lymphocyte subpopulation patterns were (1) high counts of total and helper T lymphocytes (CD3(+) and CD4(+) cells), low B lymphocytes (CD19(+) cells), and increased CD4/CD8 ratio in neonates and (2) low T lymphocytes (CD3(+), CD4(+), CD8(+) cells) with high natural killer cells (CD16(+)) and B lymphocytes (CD19(+) cells) in other groups. Low preoperative total lymphocyte counts were associated with longer intensive care unit stay in patients after bidirectional Glenn and Fontan procedure (P = .03 and P = .01, respectively) and low leukocyte counts with higher incidence of pleural effusions and chylothorax after Fontan procedure (P = .005 and P = .002, respectively). Conclusions: Single ventricle patients display several immunological abnormalities. Beyond the neonatal age, an immune pattern includes CD3(+), CD4(+), CD8(+) lymphopenia, and CD16(+) and CD19(+) lymphocytosis. B-cell lymphocytosis compensates T-cell lymphopenia, producing normal total lymphocyte counts in patients early after Fontan surgery. Low preoperative total lymphocyte counts may be associated with longer postoperative intensive care unit stay in patients with bidirectional Glenn and Fontan procedure and leukopenia with pleural effusions in Fontan patients.