H. A. Blacklock

Depletion of T lymphocytes in donor marrow prevents significant graft-versus-host disease in matched allogeneic leukaemic marrow transplant recipients.

For more than 15 years preclinical studies have suggested that acute graft-versus-host disease (aGvHD) might be prevented by the removal of immunocompetent T lymphocytes from the donor marrow inoculum. To test this observation in man 14 patients were given marrows virtually (greater than 99%) depleted of identifiable donor marrow T lymphocytes by the use of a cocktail of specific anti-T-cell monoclonal antibodies (MBG6 and RFT8) and rabbit complement. Patients were not given immunosuppressive prophylaxis after bone-marrow transplantation. Moderate to severe (grades II-IV) GvHD was totally prevented. 2 of 13 evaluable patients showed mild (grade I) skin GvHD only. Although peripheral blood recovery was slower than that obtained with other forms of GvHD prophylaxis, no fatal infections occurred. All patients survived the early post-transplant period.

USE OF ANTI-T-CELL MONOCLONAL ANTIBODY OKT3 TO PREVENT ACUTE GRAFT-VERSUS-HOST DISEASE IN ALLOGENEIC BONE-MARROW TRANSPLANTATION FOR ACUTE LEUKAEMIA

Seventeen patients who received allogeneic bone-marrow transplants from matched or slightly mismatched (in four patients) siblings were observed for at least 60 days or until acute graft-versus-host disease (GvHD) developed. All donor marrows after preliminary manipulation were incubated with 1 mg of the murine monoclonal antibody OKT3 before infusion in an attempt to deplete them of immunocompetent T lymphocytes (opsonisation). In three of the seventeen patients acute GvHD of grade II or greater developed. Two of these patients died, but they had disseminated cytomegalovirus infection as well as GvHD. Eleven patients showed no evidence of acute GvHD, and four had transient limited skin rashes (grade I GvHD). Opsonisation of T lymphocytes has reduced the incidence of severe acute GvHD in this unit from 79% in an earlier group of 14 patients to 18% when added to prophylactic methotrexate.

RAPID DIAGNOSIS OF CYTOMEGALOVIRUS INFECTION IN IMMUNOCOMPROMISED PATIENTS BY DETECTION OF EARLY ANTIGEN FLUORESCENT FOCI

Cell-cultures of cytomegalovirus (CMV) were fixed after 24 hours incubation and examined by a monoclonal antibody based immunofluorescence method for the detection of CMV-specific early antigens. 385 urine, saliva, or blood samples from 63 immunocompromised patients were inoculated onto cell-cultures. Comparison with the results of conventional cell-cultures in patients who remained uninfected showed that the new technique had a specificity of 100%. The sensitivity was 80%. This immunofluorescence method gave positive results 27h after inoculation of the specimens instead of the mean of 17 X 5 days with the conventional method based on detection of cytopathic effect. 3 saliva samples, from patients who had previously excreted CMV, reacted in the immunofluorescence method but CMV, reacted in the cell-cultures-perhaps because the assay identified defective, interfering particles in these samples. The monoclonal antibodies were also used successfully in another immunofluorescence system to diagnose cytomegalovirus pneumonitis in 3 patients by testing material obtained by bronchoalveolar lavage.

Graft rejection following HLA matched T-lymphocyte depleted bone marrow transplantation

Summary. Bone marrow graft rejection following HLA‐matched bone marrow transplantation (BMT) for leukaemia has been a rare problem. However, with the introduction of T‐lymphocyte depleted BMT, graft rejection is recognized as a new complication. At the Royal Free Hospital (RFH) in London T‐depletion is achieved using two monoclonal antibodies with complement mediated lysis. The methodology was extended to other centres and in total 56 patients have received T‐depleted, HLA matched BMT. Twelve of 56 patients have had graft rejection. At the RFH three of 41 (7%) patients have had rejection whereas at collaborating centres nine of 15 (60%) patients have had rejection. We have investigated these rejections in order to identify factor(s) responsible. Rejection was not restricted by patient or donor characteristics, nor disease status. Patient management, chemotherapy conditioning, efficiency of T‐depletion, graft versus host disease (GvHD), and infection post BMT, were not consistently implicated. The major difference between the RFH and all other centres was in the radiotherapy (RT) conditioning: The RFH prescribed a single fraction of 7‐5 Gy total body irradiation (TBI) whilst collaborating centres gave 10 or 12 Gy fractionated TBI. We conclude that the different incidence of rejection (7% v. 60%) relates primarily to the RT conditioning although the mechanisms(s) of rejection remain unknown. We conclude that where T‐depleted BMT is used, compensation by more intensive RT conditioning is required in order to avert graft rejection.

A technique for rapid isolation of bone marrow mononuclear cells using Ficoll-Metrizoate and the IBM 2991 blood cell processor

Marrow from seven normal donors and patients has been layered onto Ficoll‐Metrizoate (FM) under pressure in the IBM 2991 blood cell processor to isolate the mononuclear cell (MNC) population prior to allogeneic transplantation or cryopreservation. This separation method, which takes less than 90 min, is a further development since our previous report detailing the use of the IBM 2991 to produce a concentrated marrow‘buffy coat’for infusion (Gilmore & Prentice, 1981). By adding FM to the system, marrow stem cells are further concentrated in a small volume with removal of unwanted granulocytes and red blood cells. This facilitates the in vitro treatment of marrow with monoclonal antibodies (Granger et al, 1982) or drugs, for either the selective elimination of malignant cells prior to autologous bone marrow transplantation (BMT), or T lymphocytes in an attempt to prevent graft versus host disease (GvHD) in allogeneic BMT.

Plasma Exchange in Goodpasture’s Syndrome

The clinical course and levels of anti-glomerular basement membrane (GBM) antibody were compared in 20 patients with Goodpastures syndrome treated with plasma exchange and immunosuppression (8 patients), immunosuppression alone (4 patients) or no specific therapy (8 patients). There was a more rapid fall in the level of anti-GBM antibody and pulmonary hemorrhage was less protracted in the 8 patients treated with plasma exchange and immunosuppression. In this group, 1 patient who presented with severe renal failure showed a marked improvement of renal function and there was no progression of disease in the 4 with milder renal involvement. 2 of the 4 patients treated with immunosuppression alone, and only 2 of the 8 patients who received no specific therapy, maintained normal renal function. In the group which received no specific therapy, 1 of the 6 patients who progressed to renal failure had mild renal involvement initially. There was a significant correlation between the level of anti-GBM antibody and the severity of the morphological changes seen at renal biopsy but not between the level of anti-GBM antibody and the severity of lung hemorrhage. The course and outcome of the disease in those patients not treated, or treated with immunosuppression alone, was better than that described in early reports of this disease, while those patients with plasma exchange and immunosuppression fared even better. An adequately stratified controlled trial of immunosuppression and plasma exchange versus immunosuppression alone is in order.

ABO-INCOMPATIBLE BONE-MARROW TRANSPLANTATION: REMOVAL OF RED BLOOD CELLS FROM DONOR MARROW AVOIDING RECIPIENT ANTIBODY DEPLETION

Eight patients with acute leukaemia undergoing allogeneic bone-marrow transplantation from ABO-incompatible donors received red-cell-depleted donor marrow without any procedure to diminish their anti-ABO antibody titres. Successful marrow red-cell removal (mean 98.8%) was achieved by means of a large-volume separation technique on Ficoll-Metrizoate in the IBM 2991 blood-cell processor. Clinically significant ABO-haemolytic reaction was prevented in all patients, and there was neither failure of engraftment nor rejection. This approach used alone is satisfactory for most ABO-incompatible marrow-transplant recipients, although combining this with some method of recipient antibody depletion, such as plasma exchange, is recommended in the occasional patient with high anti-ABO titres.

A and B blood group antigen expression on mixed colony cells and erythroid precursors: relevance for human allogeneic bone marrow transplantation.

Using anti‐A and anti‐B blood group monoclonal antibodies and fluorescent activated cell sorting of human bone marrow, A (or B) blood group antigen was shown to be on 5.2 ± 5.9 (meanfSD) % of CFU‐GEMM and 12 ± 5 ± 19.6% of the erythroid burst forming cells (designated BFU‐GEMM) as defined by the mixed colony assay, and 49.5±20% of the BFU‐E and 83.5±9.9% of the CFU‐E as defined by the erythroid colony assay. This antigen expression on the BFU‐GEMM is consistent with the concept that erythroid bursts stimulated by leucocyte conditioned medium are less mature, and are closer in development to the pluripotent stem cell than the BFU‐E. These results help to explain the delayed erythropoiesis, and perhaps impaired engraftment of all cell lineages, that may occur in some recipients of ABO incompatible bone marrow transplants, with persistent and high anti‐A titres.

ELIMINATION OF T‐LYMPHOCYTES FROM HUMAN BONE MARROW WITH MONOCLONAL T‐ANTIBODIES AND CYTOLYTIC COMPLEMENT

Complement‐mediated cytolysis has been used to remove T‐lymphocytes from suspensions of human peripheral blood and bone marrow. Selective T‐cell removal was investigated by three monoclonal antibodies, OKT3, MBG6 and OKT11A. All three removed > 90% of T‐cells but combinations were necessary to kill > 99% of T‐cells in vitro. The macrophage‐granulocyte and erythroid colony forming cells of the bone marrow were spared. The method can be applied on bulk BM samples during clinical BM transplantation and will be useful to establish whether the virtually complete removal of T‐lymphocytes totally prevents transplant associated graft‐versus‐host disease in man.

Improved survival from acute lymphoblastic leukemia in adolescents and adults

Nineteen adult patients with acute lymphoblastic leukemia were treated with combination chemotherapy to induce remission in the period from 1971 to 1979. Those patients achieving remission received intensive post‐remission therapy with central nervous system (CNS) prophylaxis, followed by two‐drug maintenance therapy, and reinduction courses of chemotherapy every six months. Remissions were achieved in 17 of the 19 patients (89%). Twelve patients (63%) are alive, 11 currently in complete remission. Two patients who experienced relapses in recent months have successfully undergone transplantation with allogeneic marrow from sex‐matched, HLA‐compatible sibling donors. The median survival and median duration rates of first remissions have not yet been reached, but to date are 36+ months and 29+ months, respectively with a predicted five‐year survival rate of 61 %. These results not only are significantly better than those achieved in the years 1968 to 1971 in our institution, but also are superior to others reported in the world medical literature. The combination of optimal treatment protocols with allogeneic marrow transplantation for patients with poor prognoses is expected to improve the survival of adult patients even further in the next decade.