The effects of prolonged cardiopulmonary bypass on cell-mediated immunity.

Studies of T-cell subsets (CD3+, CD4+, CD8+, CD8+ CD57+ cells), lymphocyte response to concanavalin A (Con A), phytohaemoagglutinin (PHA) and the alterations of white cell membranes shown by scanning electronic microscope (SEM) in 51 patients who underwent cardiac operation were performed. Out of these 51 unselected patients, for 16, duration of CPB was < or = 110 min (group A), while for the other 35 (group B) it was prolonged (> 110 minutes). Although variations of the lymphocyte subset observed between groups A and B were slightly significant (p < 0.05 before CPB and on postoperative day 7), the T-cell reactivity in group B in comparison to that of group A did not normalize by postoperative day 7 regardless of stimulation with PHA or with Con A. With the use of the SEM, the folded aspect of lymphocyte surface decreased after surgery in about 71% (group A) and 78% (group B) of the observed cells. The outcome of the immunological effects given by our studies could have been due to an elongated CPB even if there need to be taken into consideration multifactorial influences, i.e. biological, pharmacological and hormonal hypotheses, and rapid changes in CPB-micro-environment.