Immunologic status in pediatric cardiosurgical patients with chylothorax

The impact of lymphocyte and immunoglobulin loss on immunologic status has not been extensively studied in children with chylothorax. The purpose of this study was to evaluate immunologic profile of pediatric cardiosurgical patients who developed infection while suffering from prolonged postoperative chylothorax.

We retrospectively reviewed immunologic findings in 16 pediatric cardiac patients with post-operative chylothorax persisting ?7 days. Patients were on total parenteral nutrition, received colloides for replacement of chylous losses, and antibiotics and/or antimycotics for treatment of infection. Immunologic evaluation included immunoglobulin levels, cellular immunity, and phagocytic activity. For every parameter z-score was calculated according to age-dependent nomograms and t-test was used to compare z-score distribution with normal distribution.

The immunoglobulin (IgG, IgM, and IgA) levels did not significantly differ from normal values, although 25% patients had IgG levels below normal range. The relative and absolute counts of peripheral blood lymphocytes were lower (p < 0.001) than normal values. Absolute numbers of blood B-lymphocytes (CD19+), T-lymphocytes (CD3+), helper/inducer T-cells (CD4+), and suppressor/cytotoxic T-cells (CD8+) were also below normal range (p < 0.001); however, their relative percentages and a CD4+/CD8+ ratio were within normal limits. The percentage and absolute number of natural killer cells (CD16+), phagocytic and metabolic activity of polymorphonuclear leukocytes did not differ from normal values.

Persisting chylothorax results in B-cell and T-cell lymphopenia with proportional decline of CD4+ and CD8+ cells. Hypogammaglobulinemia observed in other studies has not been detected in this series probably due to administered plasma. Effects of these immunologic alterations on development of infection are unknown (Tab. 2, Ref. 13).