IgG subclasses and avidity of antibodies to polysaccharide antigens in allogeneic BMT recipients after vaccination with pneumococcal polysaccharide and Haemophilus influenzae type b conjugate vaccines

In a randomized study, 20 adult allogeneic BMT recipients were vaccinated a t 6 months and 22 at 18 months after BMT with Haemophilus influenzae type b (Hib)diphtheria toroid conjugate vaccine (PRP-D), and 23 recipients at 8 m onths and 21 at 20 months with pneumococcal polysaccharide (Pnc PS) vaccine . IgG1 and IgG2, subclasses of Pnc PS and Hib antibodies and avidities of P nc PS IgG antibodies were determined by EIA in sera from patients with at l east a two-fold total antibody response to Pnc type 3, 6B, 19F or PRP-D, Th e Pnc PS vaccine induced predominantly IgG1 Pnc 3 antibody production, Anti -Pm 6B and 19F responses were mainly IgG2, The time of the Pnc PS vaccinati on, at 8 or 20 months after BMT, did not influence the IgG subclass respons e pattern, The PRP-D vaccine induced predominantly IgG2 anti-Hib production in the patients vaccinated at 6 months after BMT, The patients vaccinated at 18 months produced IgG1 and IgG2 antibodies more evenly, The same patien t was able to produce predominantly IgG1 subclass antibodies to one antigen , Pnc 3, 6B, 19F or Hib, and IgG2 antibodies to another, The avidities of a nti-Pnc 6B and 19F 1 month after vaccination were similar to those before v accination, anti-Pnc 3 avidity was lower than before vaccination but mature d in 15 months. The IgG subclass distribution and avidity were similar in t he patients with and without chronic GVHD, In conclusion the IgG response t o Pnc type 3 was predominantly IgG1 as in infants and IgG2 to PRP-D, Pnc 6B , and 19F as in adults, Early vaccination after BMT or the presence of chro nic GVHD did not impair the quality of response to Pnc PS and PRP-D vaccine s.