Serum opsonic activity after pneumococcal vaccination in splenectomized individuals as measured by a nitroblue tetrazolium (NBT) reduction micromethod.

19 children who were splenectomized after traumatic rupture and 15 healthy siblings were vaccinated with a 14-valent pneumococcal vaccine (Pneumovax). The serum opsonic activity against types 3, 6A, 7F, 14, 19F and 23F was evaluated before the vaccination and after 2 and 12 months by a new micromethod based on nitroblue tetrazolium reduction of granulocytes. Before the vaccination, opsonic activity was found more often in the splenectomized than in the controls, 38 and 29%, respectively. However, patients and controls responded similarly to the vaccine. The serum opsonic activity changed from negative to positive after vaccination in 31% of the splenectomized, as well as the controls. The results indicate that the protection against pneumococcal infection after vaccination may not be adequate against all pneumococcal types in all patients.