Immunoglobulin levels and lymphocyte subsets following cardiac operations: further evidence for a T-helper cell shifting

Abstract

Background: Recent data indicate that cardiac surgery with cardiopulmonary bypass (CPB) results in an imbalance of T-helper cell subsets towards the anti-inflammatory pathway mediating humoral immune response. However, little is known about immunoglobulin levels as an important part of humoral immune response after CPB. Therefore, the objectives of this study were 1) to elucidate the effects of CPB on perioperative immunoglobulin levels, and 2) to find out if alterations in lymphocyte subsets are related to these findings.

Methods: Blood samples from 83 patients undergoing elective cardiac operation were taken preoperatively (d0), on the first (d1), third (d3), and fifth day (d5) after operation. Levels of immunoglobulin (Ig) E, IgM, and IgG, including the subclasses IgG 1 - 4, were measured. IgG2/IgE-ratio was used as indicator for TH1/TH2 shifting, and production of tetanus antibodies (AB) was investigated as an in vivo parameter of humoral immune reaction. The number and percentage of T- and B-lymphocyte subsets were assessed in a subgroup of 50 patients to answer the second question.

Results: Clinically, no mortality or major morbidity were observed. IgE levels did not change until d3 and increased significantly on d5. In contrast, both IgG and IgM levels decreased significantly on d1. While IgM returned to baseline (BL) on d5, IgG levels remained below BL until d5. IgG2/IgE-ratio decreased significantly on d1, reached its nadir on d3 and remained depressed until d5. The number of T-lymphocytes decreased on d1 as well as the number of B-cells. T-cells returned to BL on d5, B-cells on d3. However, while the percentage of T-cells decreased on d1, the percentage of B-cells increased. The percentage of T-cells returned to BL on d3, and B-cell percentage returned to BL on d5. Tetanus AB production did not change until d5 when it increased significantly.

Conclusions: 1) Increase of IgE and tetanus AB production indicate that humoral immune response is not affected by CPB, but possibly even enhanced. The relative increase of B-cells is in line with this hypothesis. 2) Postoperative changes in immunoglobulin levels provide further evidence for a TH1/TH2-shifting. 3) The transient deficit in IgM-and IgG levels did not result in clinically adverse events. Thus, therapeutic intervention appears not to be required.