Transfer of humoral immunity against cytomegalovirus proteins following transplantation of T-cell-depleted allogeneic bone marrow from seropositive donors

Immune response to neutralizing epitope on human cytomegalovirus gylcoprotein B in Japanese: correlation of serologic response with HLA-type

Antigenic domain 1 (AD-1), located between amino acids 608 and 625 of human cytomegalovirus (CMV) gB protein, is the major domain recognized by neutralizing antibodies. Amino acids 552 to 630 are essential for the binding of neutralizing antibodies. We developed an enzyme-linked immunosorbent assay (ELISA) to detect antibodies against a fusion protein containing amino acid residues 549 to 644 of the gB polypeptide and maltose binding protein (MBP). Of 180 seropositive samples, 106 (58.9%) showed positive immuno-reactivity against the fusion protein. None of the seronegative samples reacted with the fusion protein. Among 57 seropositive individuals typed for HLA, subjects with HLA-DR9 had a higher positive rate against the fusion protein (13/14=92.9%) than those without HLA-DR9 (25/43=58.1%). In addition, subjects with HLA-DR15 had a lower positive rate against the fusion protein (7/16=43.3%) than those without HLA-DR15 (31/41=75.6%). Mean OD values of HLA-DR15-positive individuals were significantly lower than those of HLA-DR15-negative individuals. Thus, among CMV-infected individuals, HLA-DR9 may be associated with responders for neutralizing antibodies and HLA-DR15 may be associated with non/low-responders.

Persistence of Antibody to Human Parvovirus B19 After Allogeneic Bone Marrow Transplantation: Role of Prior Recipient Immunity

Human parvovirus B19 (B19) IgG was studied retrospectively in 66 allogeneic bone marrow transplantation (BMT) patients using an enzyme-linked immunosorbent assay. Recipient and donor sera had been stored pre-BMT together with sequential sera thereafter. Approximately half of donors and recipients had anti-B19 IgG pre-BMT and thus the relative contributions of donor and recipient immunity to antibody production after transplantation could be assessed. For each patient, a serum taken 2 to 3 years after BMT was also tested and the results show that persistence of B19 antibody depends on prior recipient (P = .0003) but not on donor immunity (P = .8). The findings were similar in both sibling and (VUD) BMT volunteer unrelated donor patients. Analysis of sequential post-BMT sera from 41 of the patients, for whom appropriately timed samples were available, showed primary B19 infection in 3 seronegative individuals, whereas 5 others who were seropositive before BMT underwent recurrent infection. Sequential results from the remaining 33 patients without recent B19 infection showed no evidence for donor antibody transfer and confirmed that antibody persistence depends on prior recipient immunity. B19 IgG levels decreased variably with time and some patients eventually became seronegative. It is concluded that this long-term persistence of B19 antibody post-BMT is most probably due to the existence of long-lived recipient plasma cells.

Cytomegalovirus antibody avidity in allogeneic bone marrow recipients: evidence for primary or secondary humoral responses depending on donor immune status

The reconstitution of the human cytomegalovirus (CMV) antibody response in CMV seropositive bone marrow transplant patients was investigated by comparing 11 patients whose donors were CMV seropositive with 8 whose donors were CMV seronegative. Evidence for primary or secondary responses to CMV was sought by determining IgG antibody avidity using an avidity index method, and antibody titre over a period of up to 3 years after transplant. For the patients whose donors were CMV seropositive, the results showed the characteristics of a secondary response, i.e., rising antibody titres of high avidity immediately after transplant. In contrast, the patients with CMV seronegative donors showed evidence of a primary antibody response usually occurring at about 250 days after transplant, i.e., rising antibody levels initially of low avidity maturing to high avidity over the following 100 to 200 days. It is concluded that a secondary response and hence transfer of humoral immunity had occurred in those patients whose donor was CMV seropositive, whereas a delayed primary response occurred in those patients whose donor was CMV seronegative.