Titers of antibody to pneumococci in allogeneic bone marrow transplant recipients before and after vaccination with pneumococcal vaccine.

To understand the susceptibility of allogeneic bone marrow transplant recipients to pneumococcal infection, we measured the level of type-specific antibodies to pneumococcal capsular polysaccharide in serum from ten marrow recipients. Seven recipients received marrow from matched sibling donors who had recently been vaccinated with polyvalent pneumococcal vaccine. Titers of IgG antibodies to two pneumococcal serotypes (7F and 14) declined significantly during the first year after transplantation. IgM antibodies remained low or declined after transplantation, but IgM antibodies to type 7F increased during the latter half of the first year. Pneumococcal vaccine was administered to seven marrow recipients approximately two years after transplantation. Vaccinated recipients had lower postvaccination titers of type-specific IgG antibody than did vaccinated normal adults and vaccinated sibling donors, and the recipients had normal levels of type-specific IgM antibodies. Thus, the susceptibility of marrow graft recipients to pneumococcal disease may be related to lowered concentrations of antibody to pneumococci after engraftment.