Elevated production of interleukin-2 by lymphocytes from children with acute leukemia

Musculoskeletal manifestations in pediatric acute leukemia

BACKGROUND

In children, acute leukemia (AL) at presentation can mimic several orthopaedic pathologies, so that a variable delay of the correct diagnosis is often reported.

METHODS

To define more clearly the clinical and radiological musculoskeletal manifestations of leukemia in children, 122 affected children referred from 1984 to 1999 to our Pediatric Onco-Hematologic Clinic were retrospectively reviewed. Average age at diagnosis was 6.6 years (from 7 months to 17 years). Seventy-three (60%) were boys and adolescent boys, 49 (40%) were girls and adolescent girls. One hundred two (83.6%) had acute lymphoblastic leukemia, 20 (16.4%) had acute myeloid leukemia. The mean follow-up was 8.2 years for the 104 survivors and 2.5 years for the 18 nonsurvivors. The chi2 test was used to perform the statistical analyses.

RESULTS

At presentation, complaints related to the musculoskeletal system were frequent (38.3%), including pain (34.4%), functional impairment (22.9%), limping (12.3%), swelling (10.6%), and joint effusion (5.7%). At presentation, 40.2% of children had at least 1 radiographic abnormality. In order, they were osteolysis (13.1%), metaphyseal bands (9.8%), osteopenia (9%), osteosclerosis (7.4%), permeative pattern (5.7%), pathological fractures (5.7%), periosteal reactions (4.1%), and mixed lysis-sclerosis lesions (2.5%). Different from previous reports, late radiographic lesions were uncommon (5.7%), probably because of milder newer medication protocols. They included avascular necrosis (3.3%), vertebral collapses (1.6%), and osteolysis (0.8%).

CONCLUSIONS

Both clinical and radiological changes had various and no uniform localization. Poor correlation was found between symptoms and radiological lesions. Survival rates in children with AL were 95.8% at 1 year, 89.6% at 3 years, 85.8% at 5 years, and 83.4% at 10 and at 13 years. Radiographic abnormalities (P = 0.400), type of leukemia (P = 0.291), sex (P = 0.245), and white blood cell count at presentation (P = 0.877) were not prognostic factors. The presence of multiple bone lesions did not affect the survival rate (P=0.632). As early diagnosis significantly decreases morbidity and mortality of AL, the orthopaedist should suspect AL in any child with unexplained persistent skeletal pain or radiographic alterations. Accurate history, general physical examination, and complete blood cell count tests should address the suspicion, which is confirmed by a peripheral and/or iliac crest bone marrow biopsy.

T-cell subsets, interleukin-2 receptor expression and production of interleukin-2 in minimal change nephrotic syndrome

This study was designed to investigate T-lymphocyte subsets interleukin-2 receptor (IL-2R) expression and IL-2 production in minimal change nephrotic syndrome (MCNS). Peripheral blood T-lymphocytes and IL-2R expression were analysed using fluorescein isothiocyanate-labelled CD3, CD4, CD8 and CD25 monoclonal antibodies with flow cytometry. IL-2 production was determined by enzyme immunoassay. Ten children with MCNS in relapse and in remission were evaluated. Thirteen healthy children served as controls. The patients in relapse demonstrated a moderate decrease in the total absolute lymphocyte counts and CD8(+) T-lymphocytes compared with controls (P < 0.05) and had a greatly increased IL-2R expression in freshly isolated, unstimulated peripheral lymphocytes compared with patients in remission and controls. While this was not statistically significant, IL-2R expression on cultured lymphocytes stimulated with phytohaemagglutinin was significantly elevated in relapse compared with those in remission and controls (P < 0.05). IL-2 production did not correlate well with IL-2R expression and there was no significant difference between the groups. Our results suggest that T-cell subset changes and high IL-2R expression on peripheral lymphocytes may indicate the presence of stimulated T-cell populations in MCNS which could contribute to the immunopathogenesis.

Leukaemic peripheral blood plasma and bone marrow plasma: comparison of influence on lymphocyte proliferation

Peripheral blood plasma from some children with untreated acute lymphoblastic leukaemia (ALL) exerted an inhibitory effect in vitro on phytohaemagglutinin-induced lymphocyte transformation of normal peripheral blood lymphocytes. This occurred at concentrations beyond that required for optimal response as judged by reduction of blast cell formation and tritiated thymidine and tritiated uridine incorporation into DNA and RNA, respectively. In contrast, bone marrow plasma from these patients was non-inhibitory or contained significantly less inhibitory activity. Bone marrow plasma from the majority of healthy controls was superior to their peripheral blood plasma in enhancing phytohaemagglutinin-induced mitogenesis. The difference between an individual's bone marrow- and peripheral blood-derived plasma in enhancing proliferation of patient and healthy control cells was significantly greater amongst the patients than the healthy control group; this was attributed mainly to the increased inhibitory activity of ALL peripheral blood plasma compared with normal plasma. Medium conditioned by phytohaemagglutinin-stimulated normal peripheral blood lymphocytes was effective in neutralizing the inhibitory activity of ALL peripheral blood plasma. Taken together, these in vitro results are at least suggestive that in vivo, in healthy subjects, the rapidly proliferating cells in the bone marrow and the 'resting' blood cells in the circulation may be under the influence of a fine balance of different types and/or levels of humoral growth stimulatory and inhibitory factors and that in ALL an unstable balance of these factors exists. The decreased proliferation of circulating blast cells compared with bone marrow blasts in ALL may be attributed, at least in part, to exposure to the different levels of inhibitor(s) in the circulation and bone marrow as demonstrated in vitro by our results.

Serial study of T lymphocytes in childhood leukemia during remission

Peripheral blood T lymphocyte numbers and function were studied in 22 children on UKALL X maintenance chemotherapy over a 2-year period, and results were compared with 20 healthy children. CD4 and CD8 subsets were enumerated using indirect immunofluorescence, and specific (HSV-1) and polyclonal (Con A, PWM) activation was studied by proliferation and IL-2/IL-4 production in vitro. T lymphocytes were significantly decreased with a greater fall in CD4 than CD8 T lymphocyte numbers. Proliferation responses were slightly but significantly decreased whereas IL-2 and IL-4 production were not significantly different from control values. These findings suggest that decreased numbers of CD4 helper T cells may be the most important factor in clinical immunodeficiency during maintenance chemotherapy for cALL contributing to increased susceptibility to opportunistic infections and argue against the presence of T lymphocytes with defective function.

Severe osteopenia and vertebral compression fractures after complete remission in an adolescent with acute leukemia

Acute leukemia frequently presents with skeletal symptoms; however, the etiologies of bone pain and osteopenia are poorly understood. We present the case of an adolescent girl with acute leukemia who developed vertebral fractures after being in complete remission for 3 months. Bone mineral density was very low (less than 0.6 g/cm2) but remained stable during the subsequent 3 months despite continuation therapy with methotrexate and prednisone. Findings of a bone biopsy were consistent with a recent episode of aggressive bone resorption. We suggest that paracrine secretion of lymphokines may mediate loss of bone mass during the active phase of acute leukemia, although clinical bone disease may not develop until after complete remission is achieved.

Impaired Cytotoxic Activity of Interleukin 2 (IL 2)-cultured Large Granular Lymphocytes (LGL) in Childhood Acute Lymphoblastic Leukemia. Quantitative Measurement of IL 2 Receptor Expression of IL 2-cultured LGL

Large granular lymphocytes (LGL) of the natural killer (NK) cell lineage were highly purified and their interleukin 2 (IL 2) receptors (IL 2R) were investigated in childhood acute lymphoblastic leukemia (ALL). Not only NK activity but also 3-day recombinant IL 2-cultured lymphokine activated killer (LAK) activity were decreased in ALL, despite normal percentages of LGL, CD16 (Leul1)(+) and CD56 (NKH1)(+) cells. The cytotoxic activity of IL 2-cultured LGL, but not IL 2-cultured T cells, was significantly decreased in ALL, indicating a selective defect of LGL among the killer cells. IL 2R (CD25) numbers/cell of 3-day IL 2-cultured LGL were not decreased in ALL by flow cytometric analysis. Scatchard plot analysis demonstrated that high affinity IL 2R numbers/cell of 3-day IL 2-cultured LGL were normal but the binding affinity level of the receptors in these cells in ALL was one-third of that in the similarly-cultured control cells, suggesting inadequate IL 2-IL 2R interaction is responsible, at least in part, for their reduced cytotoxic activity.

Impaired expression of interleukin 2 receptors in childhood acute lymphoblastic leukemia

Peripheral blood mononuclear cells (PBMC) from acute lymphoblastic leukemia (ALL) patients were studied for the expression of interleukin 2 receptors (IL-2R). When stimulated with phytohemagglutinin (PHA) for 3 days, the percentage of p55 Tac positive cells and the number of high affinity IL-2R was decreased in on-therapy ALL patients at remission and returned to normal after cessation of the treatment. However, the percentage of p75 IL-2R positive PBMC was normal in all ALL patients at remission. It is well-known that there are several immunological abnormalities including T and natural killer (NK) cell dysfunctions in ALL patients undergoing maintenance chemotherapy. IL-2 facilitates T-cell growth and corrects defective NK activity. Taking this into account, there may be a poor utilization of autologously produced IL-2 because of the impaired expression of IL-2R, and this poor utilization of IL-2 may be related to the defective immunological functions in childhood ALL patients at remission who are receiving maintenance chemotherapy.