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Antibody response to pneumococcal vaccine in children receiving bone marrow transplantation
M A Avanzini1, A M Carra, R Maccario
1Department of Pediatrics University of Pavia, I.R.C.C.S. Policlinico San Matteo, Italy.
Insights
Pediatric bone marrow transplant patients showed improved antibody responses to pneumococcal vaccines over time post-transplant. Recovery of immune reactivity to polysaccharide antigens is linked to the time elapsed since bone marrow transplantation.
Area of Science:
- Immunology
- Pediatric Hematology/Oncology
- Vaccinology
Background:
- Bone marrow transplantation (BMT) can impair immune function, affecting vaccine responsiveness.
- Pneumococcal polysaccharide vaccines are crucial for preventing infections in immunocompromised individuals.
Purpose of the Study:
- To evaluate the immune response to pneumococcal polysaccharide vaccine in pediatric BMT recipients.
- To identify factors influencing vaccine response rates after BMT.
Main Methods:
- Fifty-three pediatric patients received polyvalent pneumococcal vaccine (Pneumovax II) at least six months post-BMT.
- Antibody levels (IgM, IgG, IgG subclasses) were measured before and three weeks after vaccination.
- Response rates were analyzed in relation to time post-BMT, graft-versus-host disease, and sex.
Main Results:
- Vaccination significantly increased antibody serum levels (P < 0.000001).
- Response rates were higher with longer intervals post-BMT (2+ years: 100%; 1-2 years: 50%; 6mo-1yr: 20-30%).
- Time post-transplant was the primary predictor of response; IgG2 deficiency normalized in some patients.
Conclusions:
- Immune recovery to polysaccharide antigens is significantly influenced by the time elapsed since BMT.
- This supports a sequential B-cell repertoire development model where polysaccharide responses mature later.
Abstract:
Fifty-three pediatric patients given an allogeneic or an autologous bone marrow transplantation (BMT) were immunized with a polyvalent pneumococcal capsular polysaccharide vaccine (Pneumovax II). Vaccine was administered six months or more after BMT and the pneumococcal IgM, total IgG, and IgG subclasses levels were evaluated before and three weeks after immunization. Immunization promoted a significant rise in antibody serum levels (P < 0.000001), and all children vaccinated more than two years after transplantation responded to pneumococcal polysaccharides, whereas only 20-30% and 50% of patients given BMT between six months and one year and one and two years, respectively, mounted an effective antibody production (P < 0.0001). In univariate analysis, lapse of time from BMT to vaccination, chronic graft-versus-host disease occurrence, and female sex influenced the response rate. However, in multivariate analysis, only time between marrow transplant and immunization was a powerful predictor of response. Interestingly, four of 11 patients with IgG2 deficiency before immunization normalized serum levels of this IgG subclass after the pneumococcal antigenic challenge. Our study suggests that time after transplant is the major factor influencing the recovery of immune reactivity to polysaccharide antigens. This seems to confirm the hypothesis that ontogeny of the B-cell repertoire follows a predetermined sequential program in which polysaccharide antigens are some of the last to evoke an antibody response.