Cellular immunity to vaccinations and herpesvirus infections after bone marrow transplantation

The cellular immune response to herpesviruses was studied in 46 recipients of marrow grafts (23 autologous, 23 allogeneic). That study was performed in vitro by evaluating the degree of lymphocyte proliferative responses to herpes simplex virus (HSV), cytomegalovirus (CMV), and varicella zoster virus (VZV). No primary infections with any of those viruses were noted after bone marrow transplantation (BMT). The incidence of active infection in seropositive patients was significantly lower after autologous BMT than after allogeneic BMT (HSV, 2/22 vs. 11/22 patients, respectively, P = 0.007; CMV, 4/12 vs. 9/10 patients, respectively, P = 0.02; VZV, 3/23 vs. 11/23 patients, respectively, P = 0.02). After autologous BMT, the restoration of cellular immunity to the three viruses occurred at a clearly faster rate than after allogeneic BMT. That pattern may have contributed to the low incidence of active infections with those viruses after autologous BMT. Recipients of allogeneic marrow from donors with a positive lymphocyte proliferation test to HSV had a significantly increased incidence of active HSV infection post-BMT (8/9 patients) than those who received marrow from donors with a negative test (3/13 patients; P = 0.008). Acute or chronic graft-versus-host disease (GVHD) decreased the cellular immune response to the three herpes viruses, but not significantly. Our program of vaccinations with diphtheria and tetanus toxoids started in the fourth month post BMT. Chronic GVHD patients who were vaccinated had a clearly impaired cellular immune response to both toxoids as compared with those without chronic GVHD.

Is aciclovir prophylaxis necessary after bone marrow transplantation?

To assess the cost-effect relationship of aciclovir prophylaxis versus early treatment, we performed a retrospective study in 44 allogeneic bone marrow transplant recipients, who had only received aciclovir for therapeutic purposes. After bone marrow transplantation 18 herpes simplex infections occurred in 15 of the 33 patients who were seropositive for herpes simplex virus. In ten patients without clinical signs, routine viral cultures yielded herpes simplex virus. Aciclovir was given intravenously to the patients with mucocutaneous herpes infection. All infections responded rapidly. It can be calculated that restricting the drug to therapeutic use reduced the amount of aciclovir used, which in turn diminished the cost of treatment and the risk of aciclovir resistance.

Reduction and repopulation of T-lymphocytes after cytoreductive therapy with or without autologous bone marrow rescue

The reconstitution of peripheral-blood T-lymphocytes following cytoreductive therapy in standard (11 patients) or in high dosages (ten patients) was compared with that after supralethal cytoreductive therapy followed by autologous bone marrow rescue (ABMR, 20 patients). Along with the increasing cytotoxic potential of the three therapy protocols, T-cell counts fell to lower levels. Following all three forms of cytoreductive therapy, T8+ T-cell counts decreased to lower levels than T4+ T-cell counts. The greater relative reduction of T8+ T cells may indicate that T8+ T cells are more sensitive to cytoreductive therapy than T4+ T cells, and/or that T8+ T cells have shorter survival times. The contribution of residual (mainly T4+) T cells to the T-cell repopulation was significant in the patients on standard-dosage chemotherapy, less important in those on high-dosage chemotherapy, and minor in those receiving supralethal cytoreductive therapy and ABMR. The repopulation rates of T8+ T cells following ABMR exceeded those observed after chemotherapy without ABMR. The T3- (T3 negative) T-cell subset, which comprises only 5%-10% of peripheral T cells in normal individuals, decreased rapidly to low levels and remained so for the entire six-week observation period in both chemotherapy groups. Following ABMR, however, those T3- T cells rapidly increased again to normal levels. Since the T cells in bone marrow biopsies have a large T3- fraction, that rapid recovery of T3- T cells may reflect the contribution of marrow precursors in the marrow grafts to the improved T-cell regeneration following ABMR.

Influence of graft-versus-host disease prophylaxis on early T-lymphocyte regeneration following allogeneic bone marrow transplantation

An early decrease in the ratio between T4+ and T8+ T lymphocytes has been shown to correlate with the development of grade II-IV GVHD in allogeneic bone marrow transplant (BMT) recipients receiving methotrexate (MTX) as prophylaxis for acute graft-versus-host disease (GVHD). This study compares the onset of T-cell regeneration in patients receiving cyclosporin A (CyA) with those receiving MTX. Firstly, lymphoid recovery occurred at a significantly faster rate in the patients on CyA. Secondly, in those patients, the repopulation of T4+ and T8+ T cells started simultaneously, whereas in patients on MTX the repopulation of the T8+ subset lagged about a week behind that of the T4+ subset. Thirdly, the decrease in the T4/T8 ratios as a function of the lymphocyte counts occurred at a significantly slower rate in the patients on CyA than in those on MTX. Thus, the differences in the onset of T-cell regeneration in BMT recipients on CyA as compared with those on MTX abolished the correlation of the T4/T8 ratio changes with grades II-IV GVHD as described in patients receiving MTX.

Reduction and repopulation of recipient T4+ and T8+ T-lymphocytes in allogeneic bone marrow transplantation

In eight recipients of allogeneic bone marrow grafts who had sex-mismatched donors, the reduction and subsequent repopulation of T4+ and T8+ T-lymphocytes of recipient origin were studied. The origin of the donor-recipient T4+ and T8+ T cells was studied using quinacrine staining of Y chromatin combined with T-cell typing for T4 and T8. Following chemoradiotherapy and bone marrow transplantation (BMT), T cells reached their nadir at a median of five (range 1-8) days after BMT. T8+ T cells decreased at a faster rate from the peripheral blood than T4+ T cells. The first T cells that appeared in the circulation at day 12 were predominantly T4+, and a large number of them were of recipient origin. Thereafter, they gradually decreased, and the numbers of T cells of donor origin increased. In the patients who had no or only minor complications, T4+ and T8+ T cells of donor origin repopulated the blood at similar rates. This pattern, however, was modified by severe graft-versus-host disease or by cytomegalovirus infection.

Cytomegalovirus immunity in allogeneic marrow grafting

IgM and IgG class antibodies to cytomegalovirus (CMV) late antigen were studied in 58 bone marrow transplant (BMT) recipients and their donors using a sensitive enzyme-linked immunosorbent assay (ELISA) and with standard virological and histomorphological techniques. Patients who were CMV-seropositive before BMT had a significantly higher risk for active CMV infection after BMT than seronegative ones (23 of 29 vs. 3 of 26 patients; P less than 1 X 10(-6)). Transplantation of marrow from CMV-seropositive donors was associated with a higher incidence of active CMV infection after BMT than transplantation of marrow from seronegative donors (17 of 28 vs. 9 of 27 patients). Such transplantations also had a significantly higher incidence of grades II-IV acute graft-versus-host disease (23 of 29 vs. 11 of 27 patients; P = 0.007). Following BMT, the evolution of the IgG class CMV antibody response was influenced by the serological status of the marrow donor. First, a fall in IgG class CMV antibody titers during the first month after BMT was seen less often after transplantation of marrow from seropositive donors than after transplantation of marrow from seronegative donors. Second, recipients of marrow from CMV-seropositive donors who developed active CMV infection had an earlier IgG antibody response than those with seronegative marrow donors. These results suggest that the transfer of memory B and T cells occurs with the graft. Failure to mount a sustained IgM or IgG antibody response upon active CMV infection was associated with a fatal outcome.

The effect of cytomegalovirus infection on T lymphocytes after allogeneic bone marrow transplantation

The influence of cytomegalovirus (CMV) infection on peripheral T lymphocyte repopulation was studied in 59 bone marrow transplant (BMT) recipients who received either cyclosporin A (CyA) or methotrexate (MTX) as prophylaxis for acute graft-versus-host disease. We used monoclonal antibodies and single- or double-marker immunofluorescence for the quantitation of T4+, T8+ and HNK1+ T cell subpopulations. CMV infection was serologically diagnosed by an enzyme-linked immunosorbent assay (ELISA), and by viral cultures and histological studies. Among the 52 patients who were evaluable for CMV infection, one had a primary infection and 24 had CMV reactivation/reinfection after BMT. In the latter patients, increases to supranormal levels were observed in T8+ T cells and HNK1+ T cells, both in patients on CyA and in patients on MTX. Double-marker immunofluorescence revealed that the two markers were largely expressed by the same cells, which therefore had the T8+ HNK1+ phenotype. In addition, the very small subset of T4+ HNK+ T cells was slightly, but consistently, increased in the patients with CMV reactivation/reinfection. CMV infection did not influence the numbers of T4+ HNK1- and T8+ HNK1- T cells. The long-lasting presence of large numbers of T8+ HNK1+ T cells in patients who had CMV reactivation/reinfection suggests a continuing interaction between the virus and the immune system of its host.

Treatment of acute graft-versus-host disease with monoclonal antibody OKT3. Clinical results and effect on circulating T lymphocytes

Eight recipients of a bone-marrow graft from HLA-identical, MLR-nonreactive sibling donors who had developed grade II-IV acute graft-versus-host disease (aGVHD), were given 14 consecutive daily injections of 5 mg of a murine anti-T-cell monoclonal antibody (MCA) called OKT3. Four patients with grade II aGVHD showed a complete response; two patients with grade II had a partial response, and two patients (one with grade II and one with grade IV) showed no improvement at all. The main side effect was a high spiking fever after the first injection. T cells were monitored with monoclonal antibodies, indirect immunofluorescence, and flow cytometry. Circulating T3+ T cells dropped to virtually zero within 1 hr following the first injection. Low numbers of E-rosetting cells were still demonstrable during OKT3 therapy. During the second week of treatment, T-cell markers (T3, T4, T8) started to increase again, in spite of excess antibody in the circulation. At that time, T cells showed weaker fluorescence with OKT3 than before OKT3 therapy, suggesting modulation of the T3 antigen. After cessation of OKT3 therapy, T cells reached pretreatment levels within one week. None of the six patients studied developed anti-mouse-Ig antibodies. These results suggest that OKT3 therapy is effective in limited aGVHD. The absence of anti-mouse-Ig antibody formation may allow repeated courses of MCA that may add to their therapeutical potential.

T lymphocyte repopulation and differentiation after bone marrow transplantation. Early shifts in the ratio between T4+ and T8+ T lymphocytes correlate with the occurrence of acute graft-versus-host disease

Acute graft-versus-host disease (GVHD), a major complication of allogeneic bone marrow transplantation (BMT), is probably mediated by T lymphocytes present in the marrow graft. In this study, the repopulation of the peripheral blood with T4+ and T8+ T cells was investigated during the period preceding the occurrence of acute GVHD. Twenty-four allogeneic and 11 autologous BMT recipients were monitored from day 4 post-BMT onward by the use of monoclonal antibodies, indirect immunofluorescence, and flow cytometry. The recipients of allogeneic transplants received methotrexate as GVHD prophylaxis. Similar recovery patterns for T4+ and T8+ T cells were found following autologous and allogeneic BMT. However, lymphoid repopulation occurred at a clearly faster rate after autologous BMT. T4+ T cells were the first to reappear in the peripheral blood, followed by T8+ T cells 4-7 days later. The T8+ T cell reconstitution occurred at an even faster rate in patients who were to develop grade II-IV GVHD, as compared with those with grade O-I GVHD, thus leading to an earlier decrease in the T4/T8 ratio. Of 10 patients with a T4/T8 ratio less than 2.5 at day 19, 9 developed grade II-IV GVHD and 1 showed no GVHD. Of 14 patients with a ratio greater than 2.5 at that time, only 2 developed grade II-IV and 12 grade O-I GVHD (p less than 0.001). In the 11 patients developing grade II-IV GVHD, the T4/T8 ratio decreased to values less than 2.5 before the first clinical symptoms of GVHD in 9; it coincided in one and occurred later in another patient. Thus, early monitoring of the T4/T8 ratio can distinguish patients at risk of developing grade II-IV GVHD.

Factors influencing platelet survival during antilymphocyte globulin treatment

The antiplatelet effect of antilymphocyte globulin (ALG) was studied during 49 courses of therapy of 4-5 d given to 43 patients with severe aplastic anaemia. Concomitant corticosteroid therapy was usually given in moderate ( MDC ) dosages from 10 to 30 mg daily (40 courses); in nine courses the ALG infusions were combined with high dose (20 mg/kg) methylprednisolone (HDC). Clinical side effects were mainly seen during the first ALG infusion. In all MDC -treated patients a decrease of the peripheral-blood leucocyte count to 20-30% of the pretreatment level during the first ALG infusion was associated with a severely shortened platelet survival. During subsequent infusions, which were tolerated much better, the survival of transfused platelets increased considerably. In the HDC-treated patients platelet survival was only slightly shortened on the first day of therapy, but the decrease of the leucocyte count was also less in these patients. Diffuse intravascular coagulation, circulating immune complexes and complement activation were excluded as major causes of the shortened platelet survival. Although ALG reacted with platelets in vitro and in vivo (as detected with indirect immunofluorescence), bystander destruction was likely during the first ALG infusion when massive leucocyte destruction occurred.

The HLA-system in immune thrombocytopenic purpura: its relation to the outcome of therapy

The distribution of HLA-A, -B, -C and -DR antigens was investigated in 154 patients with immune thrombocytopenia (99 adults and 55 children). An increased frequency of HLA-Bw56 (a split of HLA-Bw22) was found both in the adults (RR = 4.30) as well as in the children (RR = 7.91). Differences in HLA antigen distributions have also been analysed in patient subgroups with a good and a bad response to corticosteroids and splenectomy. The frequency of HLA-DR4 was low in those patients with a good response to prednisone as compared with those with a poor response. The opposite was found in splenectomized patients. In 22 patients who did not respond to splenectomy, LB4 (a local split of HLA-DR4) was completely absent. These results suggest that HLA-DR4 (LB4) may be a predictive marker for therapy in ITP patients, i.e. a bad response to corticosteroids and a favourable outcome of splenectomy. However, none of the differences were significant after correction was made for the number of antigens tested.

Long-term follow-up study of 168 patients with immune thrombocytopenia. Implications for therapy

A total of 168 patients (90 adults, 78 children) with immune thrombocytopenia (ITP) and a median follow-up of 75 months were treated with a sequential regimen of corticosteroids (n = 125), splenectomy (n = 83) and immunosuppressives (n = 25). In 43 patients an observation period of a minimum of 1 month preceded the therapy. It is concluded that: (i) withholding therapy in the expectation of spontaneous recovery is at least in children justified in case of limited bleeding tendency; (ii) corticosteroids should be limited in adults to a maximum of 3 weeks and in children to a maximum of 6 weeks; (iii) if corticosteroids fail, splenectomy remains the therapy of choice, especially in patients aged less than or equal to 30 years, and should be performed within 6 months after diagnosis; (iv) after failure of the aforementioned forms of therapy, there is rarely a beneficial effect of treatment with azathioprine and vincristine; (v) no reaction to any form of therapy can be followed by an acceptable long-term outcome.

Comparison of complement-dependent cytotoxicity and indirect immunofluorescence for enumeration of T-cell subpopulations in human peripheral blood

The monitoring of T-lymphocyte subsets of recipients of organ grafts enables studies on immune reconstitution (after bone-marrow transplantation) and may predict graft rejection (after kidney transplantation). Quantitation of human peripheral T-lymphocyte subsets from healthy volunteers and from recipients of a bone-marrow graft by a complement dependent cytotoxicity (CDC) assay, based on the use of propidium iodide, and by an indirect immunofluorescence (IIF) technique has been compared using the monoclonal antibodies OKT3, OKT4 and OKT8. Except for OKT3 in healthy individuals--for which no significant difference was found between CDC and IIF--CDC detected significantly more cells of each subset than IIF. Furthermore, the CDC results indicated the presence of low numbers of OKT4+8+ cells in the peripheral blood of healthy individuals and--with higher numbers--following marrow transplantation. Results of depletion experiments, obtained by fluorescence activated cell sorting (FACS) for either OKT4 or OKT8, supported this conclusion. OKT4/OKT8 ratios were calculated from enumerations by the CDC assay and by the IIF assay and found to be linearly related, both in healthy persons and in marrow-graft recipients. Thus, the CDC assay is a reliable method for monitoring T-cell subsets, allowing detection of lymphocytes carrying low densities of membrane determinants.

A minor transplantation antigen detected by MHC-restricted cytotoxic T lymphocytes during graft-versus-host disease

Transplantation of bone marrow can give rise to graft-versus-host disease when donor T lymphocytes, mismatched with the host for major histocompatability (MHC) antigens, become sensitized and attack host tissues. However, graft-versus-host disease can also arise between donor and host with compatible MHC antigens but mismatched for a minor histocompatability antigen. We report here on the occurrence of severe acute graft-versus-host disease in a male patient with acute myeloid leukaemia who had received bone marrow matched for MHC (HLA) antigens from his sister. Strong cytotoxicity of the posttransplantation (that is, donor) lymphocytes against the patient's pretransplantation lymphocytes was found. Thus, the transplanted lymphocytes differed in a non-HLA antigen from the patient. The possible role of this strong cytotoxic minor histocompatability antigen in the development of graft-versus-host disease in man is being evaluated. Furthermore, with the use of cytotoxic T-cell lines, derived from the patient's 6 day effector cells, we are now able to type for it before grafting.