EFFECT OF IMMUNOSUPPRESSION AFTER CARDIAC TRANSPLANTATION IN EARLY-CHILDHOOD ON ANTIBODY-RESPONSE TO POLYSACCHARIDE ANTIGEN

Background Three children who had cardiac transplantation before age 4 years later presented with recurrent sinopulmonary infection caused b y organisms including Streptococcus pneumoniae, in which capsular poly saccharide plays an important part, one developed bronchiectasis. We t herefore studied responses to polysaccharide antigen after immunosuppr ession started in early childhood. Methods Antibodies against pneumoco ccal and haemophilus polysaccharides, and total IgG, IgG1, IgG2, and I gA concentrations were measured in 33 cardiac-transplant recipients tr ansplanted before the age 4 years (group 1) and after that age (group 2). Patients with low pneumococcal and haemophilus antibody concentrat ions were immunised with 23 polyvalent pneumococcal and tetanus-haemop hilus conjugate vaccines and antibody responses were measured. Finding s Five patients from group 1 and seven from group 2 were transplanted for congenital heart disease and ten patients in each group had heart transplants because of cardiomyopathy; none were asplenic. Group 1 (16 patients) were aged 2-10 years when investigated, group 2 (17 patient s), were 6-16 years. Four of 16 patients in group 1 responded to pneum ococcal polysaccharide vaccine compared with 14 of 17 in group 2 (p=0. 0016). This difference remained when those in group 1, aged less than 4 years at investigation, were excluded (p=0.0060). Response to haemop hilus-conjugate vaccine was similar in both groups (14 of 16 vs 14 of 17, p=1.0). Significantly more patients who failed to respond to pneum ococcal vaccine had low IgG2 concentrations (p=0.0269). Interpretation Children who had a transplantation and immunosuppression in early chi ldhood before they had developed antibody responses to pneumococcal po lysaccharide, still failed to show a response when older-ie, when such responses are the norm. Ongoing immunosuppression prevents the matura tion of antipolysaccharide responses leaving children susceptible to s evere and recurrent damaging infection.