Fas-mediated apoptosis with normal expression of bcl-2 and p53 in lymphocytes from aplastic anaemia.

In order to investigate the involvement of apoptosis in the pathogenesis of aplastic anaemia (AA) we measured the expression of the Fas receptor (membrane protein that triggers apoptosis), Fas ligand (FasL), bcl-2 (cytoplasmatic protein that blocks apoptosis) and p53 (nuclear protein that induces apoptosis) in CD3 and CD19 lymphocytes from the peripheral blood or bone marrow of controls, patients with AA, aplastic anaemia in complete remission (AA-CR) and multiply transfused patients without aplastic anaemia. The Fas receptor was overexpressed in both T and B lymphocytes from the peripheral blood and bone marrow from patients with AA. These abnormalities were not detected in AA-CR or multiply transfused patients. CD3/FasL cells were not increased and no FasL expression was detected in B lymphocytes. Bcl-2 was highly expressed in lymphocytes from controls, AA, AA-CR and multiply transfused patients (> 99% of positive cells) whereas p53 was not detected in any group. To further characterize the functional activity of the Fas receptor we performed a Fas-induced apoptosis assay in peripheral blood lymphocytes using an anti-Fas monoclonal antibody. The crosslinking of the Fas receptor transduced an increased apoptotic signal in lymphocytes from AA patients, but not in lymphocytes from controls, AA-CR patients or multiply transfused patients. Taken together, these data suggest that a Fas-based mediated apoptosis without the apparent participation of bcl-2 or p53 is a possible mechanism of lymphocyte depletion in patients with AA. In addition, these findings suggest that Fas expression is a continuous event occurring from progenitor bone marrow cells to mature cells.

Increased dexamethasone-induced apoptosis of thymocytes from mice exposed to long-term extremely low frequency magnetic fields.

To address the effect of extremely low frequency electromagnetic fields on programmed cell death we assessed both the spontaneous and dexamethasone (Dex)-induced apoptosis of thymocytes and spleen cells from mice submitted to a long-term continuous exposure of a 0.4-1.0 microT 60 Hz magnetic field or an 8-20 microT direct current (DC) magnetic field. Dex-induced apoptosis but not spontaneous apoptosis was substantially increased in thymocytes from 0.4 to 1.0 microT 60 Hz field-exposed animals. Spontaneous apoptosis and Dex-induced apoptosis of spleen cells were not affected by the 0.4-1.0 microT 60 Hz field exposure. In addition, spontaneous apoptosis and Dex-induced apoptosis of thymocytes and spleen cells from mice exposed to an 8-20 microT DC field were similar to the controls. These findings represent the first demonstration that thymocytes from mice exposed to a long-term 0.4-1.0 microT 60 Hz field may show abnormal response to Dex apoptotic stimuli.

Increased apoptotic cells in bone marrow biopsies from patients with aplastic anaemia.

In order to investigate the involvement of apoptosis in the pathogenesis of aplastic anaemia (AA) we determined the proportion of apoptotic cells in paraffin-embedded bone marrow biopsies from patients with aplastic anaemia using an in situ TdT-catalysed DNA nick end labelling (TUNEL) staining method. A significant increase in the proportion of mononuclear apoptotic cells was demonstrated in biopsies from patients with aplastic anaemia (8.19 +/- 1.45%) when compared with controls (2.07 +/- 0.86%). These data support the view that apoptosis may play a role in the pathophysiology of bone marrow failure.

Anti-PGL1 levels in leprosy patients and their contacts.

1. We determined the anti-PGL1 levels of 402 individuals from the Ribeirão Preto region since the phenolic glycolipid (PGL1) is a specific Mycobacterium leprae antigen. This group consisted of 47 leprosy patients (26 with the lepromatous form, 16 with the tuberculoid form and 5 with the borderline form), 12 tuberculosis patients, 19 leprosy contacts, and 324 healthy blood donors from the Hemocenter of the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo. Anti-PGL1 levels were detected by ELISA. 2. Anti-PGL1 levels were normal in patients with tuberculoid and borderline leprosy, in tuberculosis patients and in almost all of the healthy blood donors. Patients with untreated lepromatous leprosy had elevated anti-PGL1 levels while most patients under treatment (9/16) had normal anti-PGL1 levels. Only 3% of blood donors (10/324) had elevated anti-PGL1 levels, but when these individuals were submitted to clinical and bacilloscopic examination no signs of disease were found. To complete the clinical investigation, these 10 subjects were submitted to the Mitsuda reaction which was negative in 3 of them. All of these 10 subjects are being monitored, since they may be at risk to develop leprosy. 3. On the basis of the present data, it seems that ELISA is a potentially important assay for the detection and chemotherapy of subclinical leprosy, permitting the control of epidemic centers of the disease.

Anti-PGL1 levels in leprosy patients and their contacts

1. We determined the anti-PGL1 levels of 402 individuals from the Ribeir ao Preto region since the phenolic glycolipid (PGL1) is a specific Mycobacterium leprae antigen. This group consisted of 47 leprosy patients (26 with the lepromatous form, 16 with the tuberculoid form and 5 with the borderline form), 12 tuberculosis patients, 19 leprosy contacts, and 324 healthy blood donors from the Hemocenter of the University Hospital, Faculty of Medicine of Ribeir ao Preto, University of S ao Paulo. Anti-PGL1 levels were detected by ELISA. 2. Anti-PGL1 levels were normal in patients with tuberculoid and borderline leprosy, in tuberculosis patients and in almost all of the healthy blood donors. Patients with untreated lepromatous leprosy had elevated anti-PGL1 levels while most patients under treatment (9/16) had normal anti-PGL1 levels. Only 3 per cent of blood donors (10/324) had elevated anti-PGL1 levels, but when these individuals were submitted to clinical and bacilloscopic examination no signs of disease were found. To complete the clinical investigation, these 10 subjects were submitted to the Mitsuda reaction which was negative in 3 of them. All of these 10 subjects are being monitored, since they may be at risk to develop leprosy. 3. On the basis of the present data, it seems that ELISA is a potentially important assay for the detection and chemotherapy of subclinical leprosy, permitting the control of epidemic centers of the disease