THE ANTIBODY-RESPONSE AFTER IMMUNIZATION WITH PNEUMOCOCCAL POLYSACCHARIDE VACCINE IN SPLENECTOMIZED MICE - THE EFFECT OF RE-IMMUNIZATION WITH PNEUMOCOCCAL ANTIGENS

Splenectomized individuals are at increased risk of acquiring fulminan t pneumococcal infections. In an experimental mouse model, we have stu died how removal of the spleen influences the anti-pneumococcal antibo dy response to s.c. primary immunization with a 23-valent pneumococcal polysaccharide vaccine and to re-immunization 5 months later. In sple nectomized BALB/c mice the antibody response to serotypes 1, 4, 7F, an d 19F was reduced both after the first and after the second immunizati on compared to in normal mice. In contrast, splenectomized and normal CBA/J mice produced similar antibody levels to serotypes 1 and 4 after the second immunization, although the response to these serotypes was reduced in splenectomized mice after the first immunization. After i. v. injection with heat-killed pneumococci serotype 4, splenectomized B ALB/c mice that had been immunized 5 months earlier with 23-valent vac cine were able to mount higher antibody levels which were reached earl ier than in unprimed splenectomized mice. However, normal mice that ha d been vaccinated 5 months earlier had the highest antibody levels aft er immunization with pneumococci. Our results indicate that although s plenectomized mice generally do not reach as high antibody levels as a re seen in normal mice after pneumococcal immunization, they benefit f rom previous immunization with regard to antibody levels when given a second antigen challenge.