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Engraftment in relation to infused CD34+ cell number was retrospectively analysed in 66 patients with hematological diseases: non-Hodgkin's lymphoma (n = 33), multiple myeloma (n = 21), acute myelogenous leukemia (n = 7), Hodgkin's disease (n = 4) and myelodysplastic syndrome (n = 1). Progenitor cells were mobilized with rhG-CSF, alone or in association with chemotherapy. The cells were harvested by leukapheresis until at least 2 x 10(6) CD34+/kg body weight were obtained. A total of 194 leukaphereses were performed (median = 3 per patient, range 1-9). A median of 3.40 x 10(8) nucleated cells/kg (range 0.31-27.59) and a median of 7.15 x 10(6) CD34+ cell/kg (range 1.31-115.70) were transplanted. Regardless of transfusional support or patient diagnosis, engraftment was rapid in patients who had received > or = 5 x 10(6) CD34+ cell/kg. In this case, absolute neutrophil blood count > or = 0.5 x 10(9)/l was obtained on day 12 post graft (range 7-19) and platelet count > or = 20 x 10(9)/l was also reached after the same median time interval (range 8-121). From the present results, a minimal threshold of 5 x 10(6) CD34+ cell/kg appears to be suitable for providing rapid and complete hematopoieitc reconstitution in patients exposed to high doses of chemotherapy with or without total body irradiation. Furthermore, administration of rhG-CSF during post-graft period significantly decreased the neutrophil time recovery (P = 0.002) but not that of platelets (P > 0.05).

Cord blood hematopoietic progenitors undergo circadian and seasonal variations. The lowest values are obtained between 4:00 and 12:00, as well as between May and August. This represents the first observation of such rhythms before birth.

In mammals, reproduction involves two potentially incompatible mechanisms: viviparity and development of a competent immune system. Thus the maternal and foetal organisms must respond by developing immunologic tolerance. The phenomenon does not involve total immunosuppression, but includes several highly precise processes initiated at conception. It is known that cell- and humour-mediated processes occur but their relative importance remains to be elucidated. Cytokines, especially those mediating T-helper2 cell response appear to play a predominant role in inducing immunologic tolerance to the foetal allograft. A better understanding of these mechanisms could have major implications in the diagnosis and treatment of repeated miscarriage and unexplained infertility.

Haematological recovery after autologous bone marrow transplantation (BMT) for acute myeloid leukaemia (AML) is often delayed and available laboratory assays cannot accurately predict speed of engraftment. By using the long-term bone marrow culture (LTBMC) method, we attempted to define the haemopoietic defect underlying this slow engraftment, and assessed the usefulness of LTBMC in predicting engraftment. Cryopreserved bone marrow (BM) harvested from three different groups (AML autografts, n = 18; autografts for non-leukaemic diseases, n = 23; normal donors. n = 10) were cultured and their growth was compared and correlated with the speed of engraftment. In the AML autografts, non-adherent and adherent progenitor production was significantly reduced compared with normal BM during the whole culture period (P < 0.01). None of the LTBMC parameters was found to correlate with engraftment after autologous BMT. The non-leukaemic autografts showed progenitor production intermediate between normal and AML autografts. Their progenitor content at the end of the culture period (reflecting the stem cell pool) was not statistically different from normal BM. In this group, most of the progenitor cell contents, during LTBMC correlated with neutrophil (rs = -0.618 to -0.879, P < 0.01) and platelet (rs = -0.479 to -0.707, P < 0.02) recovery. The conclusion drawn from these results is that AML autografts are defective in their ability to sustain in vitro haemopoiesis, but this in vivo defect does not correlate with the slow haemopoietic recovery after autologous BMT. In contrast, LTBMC of autografts for non-leukaemic diseases, whose defect affects the stem cell pool to a lesser extent than BM in AML correlates with the speed of engraftment.

We investigated a group of Belgian HCV-100 Elisa positive volunteer blood donors for potential sources of contamination and the presence of liver biochemical abnormalities. In addition, results of serological testing and liver biochemistry of their related blood products recipients were also analysed. In blood donors, anti-HCV-100 repeat reactive rate was 0.77% with a 34% rate of abnormal liver function tests. A potential source of parenteral exposure was found in all donors with RIBA-confirmed HCV-100 positivity. Among recipients, anti-HCV-100 RIBA-2 positive blood product donations were associated with RIBA-2 seroconversion, a history of transfusion in donors being of high predictive value of infectivity.

One hundred and seven consecutive patients with acute non-lymphocytic leukemia (ANL) aged less than 56 years were allocated to receive either allogeneic (allo-BMT) or autologous bone marrow transplantation (auto-BMT) when first complete remission (CR1) was achieved. CR was obtained in 96 patients. Twenty-four patients had an HLA-identical sibling donor and 20 of these (83%) had an allograft in CR1. Thirty-three patients (44% of the CR1 patients without donor) had an autograft in CR1. The reasons for not transplanting patients in CR1 were early relapse (nine patients), refusal (11 patients) or medical problems (23 patients). The 4-year leukemia-free survival (LFS) probability for all the CR1 patients was 25%. For the allo-BMT patients, the 4-year LFS was 71%, and for the auto-BMT patients 31% (log-rank p = 0.028). The relapse probabilities were 33% and 48% respectively (p = 0.40). If the results are analysed according to the intent of the protocol, patients with a donor had an LFS of 53%, and patients without a donor an LFS of 16% (p = 0.003). This study confirms the value of allo-BMT for consolidation of ANL in CR1. The attempt to autograft all CR1 patients without a compatible donor has not resulted in any marked improvement of LFS.

Forty patients who had had at least two early spontaneous abortions, i.e. before the 12th week of pregnancy without known aetiology factors (anatomical, chromosomal, infectious or hormonal) were immunised with their husband's leucocytes. These immunisations were carried out by repeated intravenous injections of leucocytes taken from the husband's peripheral blood. In 24 patients the search for anti-HLA antibodies was shown to be positive after a varying number of injections (2 to 10). Twelve patients are still being treated, 4 did not make antibodies. Eighteen pregnancies have been observed, of whom 11 have so far come to term, 4 are following a normal course and 3 pregnancies were interrupted late of different reasons. The success rate, by which is meant pregnancies without early abortion, was 17/21, i.e. 81%. A comparison of the number of HLA A, B or DR antigens found to be shared between the couple in 40 couples studied, when compared with a series of 64 fertile couples (who had had at least 2 children without any abortions) shows no differences. These couples as compared with fertile couples do not show either differences in the frequency of HLA antigens. After leucocyte immunisation an inhibition in the mixed lymphocyte culture is found between the patient's lymphocytes and her husband's in the wife's serum if this has made anti-HLA antibodies.

Three cases of D-penicillamine (DPA) induced myasthenia gravis (MG) and one case of DPA-induced polymyositis (PM) are reported among four patients suffering from seropositive rheumatoid arthritis. The cumulative doses responsible for the three DPA-induced MG cases amounted respectively to 73, 117 and 467 g. The cumulative dose responsible for the DPA-induced PM case amounted to 465 g. All the patients were HLA DR1. All four cases healed completely after withdrawal of DPA. The aetiology of the cases is discussed and the literature is reviewed. These cases represent further instances of DPA-induced neuromuscular disorders.

Association between HLA haplotypes and long survival was investigated in 116 children with acute lymphoblastic leukaemia. It was found that patients with A2 B12 and/or A2 B40 haplotypes survived longer than patients wtihout these two haplotypes. Since all children were treated with transfer factor obtained from their relatives, it is suggested that children possessing A2 B12 or A2 B40 haplotypes may respond better to this type of immunotherapy.

A family with high prevalence of ankylosing spondylitis (A.S.) was investigated for the presence of HL-A27. In this family, classical A.S. occurred in five subjects and possible A.S. in two out of 64 members examined. In all seven cases, HL-A27 was present. The study of the segregation of A.S. and HL-A27 in this kindred demonstrates that more than one gene is responsible for the expression of A.S., that the homozygous state for the HL-A27 gene may lead to the occurrence of A.S., and that possibly a simple genetic explanation accounts for the simultaneous transmission of HL-A27 and A.S.