Antigen-specific antibody responses of lymphocytes to tetanus toxoid after human marrow transplantation.

In vitro IgG anti-tetanus toxoid (IgG anti-TT) antibody produced by peripheral blood lymphocytes (PBL) from 16 normal subjects (9 marrow donors and 7 random healthy subjects) and 17 marrow graft recipients from 45-1058 days postgrafting was measured with an enzyme-linked immunosorbent assay (ELISA). PBL from 11 of 13 seropositive (anti-TT greater than or equal to 1:1024) normal subjects produced IgG anti-TT in vitro, whereas the PBL from the 3 seronegative (IgG anti-TT less than 1:1024) normal subjects did not. In our normal subjects, there was a high correlation between seropositivity and in vitro IgG anti-TT production (P = .0048, chi 2, two-tailed). PBL from only one of 13 seropositive marrow graft recipients produced in vitro IgG anti-TT antibody. B and T cell functions of 8 marrow graft recipients were assessed by coculturing their T and B cells with those from their HLA-identical marrow donors. One short-term patient and 7 long-term patients (4 with and 3 without chronic graft-versus-host disease) were studied. Recipient B cells failed to produce antibody in the presence of donor T cells in 7 of these 8 cases. However, T cells from long-term survivors provided helper activity to immune donor B cells in 7 of 9 evaluable cases. TT-specific helper T cell activity was present in most seropositive long-term recipients, and B cells from marrow recipients failed to produce specific antibody in the presence of normal donor TT-specific helper T cells. These results, TT-specific T cell helper activity, and normal circulating serum IgG anti-TT antibody levels in marrow graft recipients without postgrafting TT boosters suggest that specific immunity had been transferred from the marrow donor to the marrow recipient.