Pneumococcal vaccination after heart and liver transplantation. Immune responses in immunosuppressed patients and in healthy controls

Among other effects, therapeutic immunosuppression after organ transplantation impairs antibody formation. But because of the increased risk of infection, the efficacy of prophylactic immunization is of particular importance in patients after transplantation. For this reason the immunogenicity after immunization against pneumococcus was investigated in transplanted patients. A 23-valent vaccine of capsular polysaccharides (Pneumovax 23) was administered to 31 patients 4-85 months after transplantation (16 hearts transplants, 15 liver transplants; age range 22-63 years). The same immunization was given to 23 healthy control subjects. The immune response was measured serologically in all groups. Immunization was well tolerated by all participants, and there were no infectious or systemic side effects. Mean postvaccinal global pneumococcus-specific antibody titres were comparable in the healthy and transplanted subjects (controls: 5490 U/ml, heart transplanted: 5513 U/ml, liver transplanted: 4148 U/ml; differences not significant). Analysis of individual titres for the nine most important serotypes showed comparable results for six serotypes, reduced titres being found for serotypes 3 and 8 after heart transplantation, and for serotypes 8 and 23 after liver transplantation. Safe antipneumococcal immunization is possible during therapeutic immunosuppression after heart or liver transplantation. The achieved immune response is comparable to that in healthy controls. The high efficacy of the pneumococcal vaccine, compared with other vaccines, in immunosuppressed patients may be due to T-cell dependent antibody production against polysaccharides.