A new method was developed for detection of monoclonality at the DNA level in B-lymphoproliferative disease using the polymerase chain reaction and consensus primers for the V and J regions of the immunoglobulin gene. Monoclonality was detected in DNA from 15 of 15 clonal B-lymphoblastoid cell lines and from 19 of 23 cases of B- lymphocyte neoplasia, but not from any of 16 normal T-lymphocyte clones, 9 cases of T-lymphocyte neoplasia, 20 samples of polyclonal peripheral blood lymphocytes, and 8 cases of reactive lymphadenopathy. This method for detection of monoclonality is likely to be of routine value in diagnosis owing to its simplicity, speed, and versatility.

Chemokine receptor/ligand interactions orchestrate the migration of cells to peripheral tissues such as the skin. We analysed chemokine receptor expression by acute myeloid leukaemic (AML) cells present in peripheral blood (n = 7), bone marrow (n = 6), or skin (n = 11) obtained from 15 paediatric AML patients with skin involvement and in 10 AML patients without skin involvement. High percentages of circulating CCR2(pos) AML cells were only detected in patients with extramedullary disease. Skin-residing AML cells displayed a different set of receptors in situ, namely: CCR5, CXCR4, CXCR7 and CX3CR1. These results suggest the involvement of different chemokine/chemokine receptor interactions in homing and retention of AML blasts in the skin.

Summary.Immune abnormalities have been reported in recipients of cellular and plasma blood products. To document the effect of current transfusion practices, we performed ex vivo lymphocyte immunophenotypic studies on patients with thalassaemia major who had received multiple (leucocyte-depleted) transfusions and patients with haemophilia A and B who had received heat viral-inactivated factor concentrates. Patients with thalassaemia major showed a significant lymphocytosis, with mainly B-cell changes consistent with ongoing B-cell stimulation associated with chronic exposure to red cell antigens. Reduced T-cell IL-2Ra expression would be consistent with inhibition by desferrioxamine chelation therapy. In contrast, patients with haemophilia showed predominantly T-cell changes. Patients with haemophilia A showed significantly elevated activated CD8 þ cytotoxic T lymphocytes whereas those with haemophilia B showed an increase in CD8þ CD11a dim and CD4suppressor T cells. Several of the immune abnormalities found may be due to the presence of cytokines not removed by leucocyte filtration or destroyed by factor concentrate production (e.g. TGF-b) causing a T-helper-2-like response. The extensive lymphocyte characterization in this study has not previously been performed and has enabled a closer examination of the functional lymphocyte immunophenotypes seen in patients treated according to current transfusion practices.

Cord blood has been used successfully for stem cell transplantation in several haematological conditions: Fanconi's anaemia, leukaemia and Wiskott-Aldrich syndrome. On account of the low incidence of GVHD observed following cord blood transplantation, it has been suggested that cord blood be used for HLA-matched, or perhaps one or two antigens mismatched. and unrelated stem cell transplantation. Based on an extensive immunophenotypefunctional correlation, we determined that cord blood contains mainly immature unprimed T lymphocytes that are predominantly suppressor cells. Recent findings suggest that dysregulated production of cytokines (IL-1, IL-2, TNFa) plays a role in GVHD. We showed that T cells in cord blood express receptors for IL-2, TNFa, but no receptors for 11,-1. Similarly. NK cells, one of the effector cells of GVHD, express receptors for TNFa and y1FN but do not express receptors for IL-1, nor IL-2R a-chain (CD25) although IL-2R P-chain is expressed. The potential for activation of T lymphocytes and NK cells therefore exists in the context of bone marrow transplantation. However, the high number of suppressor cells in cord blood most likely modulate the activation of lymphocytes and NK cells thereby minimizing GVHD.

Bone marrow architecture is grossly distorted at the diagnosis of ALL and details of the morphological changes that accompany response to Induction chemotherapy have not been reported before. While marrow aspirates are widely used to assess initial response to ALL therapy and provide some indications, we have enumerated marrow components using morphometric analysis of trephine samples with the aim of achieving a greater understanding of changes in bone marrow niches. Morphometric analyses were carried out in the bone marrow trephine samples of 44 children with ALL, using a NanoZoomer HT digital scanner. Diagnostic samples were compared to those of 32 control patients with solid tumors but without marrow involvement. Samples from patients with ALL had significantly increased fibrosis and the area occupied by bony trabeculae was lower than in controls. Cellularity was higher in ALL samples due to leukemic infiltration while the percentage of normal elements such as megakaryocytes, adipocytes, osteoblasts and osteoclasts were all significantly lower. During the course of Induction therapy, there was a decrease in the cellularity of ALL samples at day 15 of therapy with a further decrease at the end of Induction and an increase in the area occupied by adipocytes and the width of sinusoids. Reticulin fibrosis decreased throughout Induction. Megakaryocytes increased, osteoblasts and osteoclasts remained unchanged. No correlation was found between clinical presentation, early response to treatment and morphological changes. Our results provide a morphological background to further studies of bone marrow stroma in ALL.