02833nas a2200301   4500000000100000008004100001260001300042653001200055653001100067653001100078653002200089653001200111653000900123653000900132653002500141653002500166653001800191653001500209653002700224100001400251700001300265245017700278856004100455300001000496490000700506520200400513022001402517       2002                            d  c2002 Mar10aAnimals10aFemale10aHumans10aImmunosuppression10aleprosy10aMale10aMice10aMicroscopy, Electron10aMycobacterium leprae10aSciatic Nerve10aThymectomy10aWhole-body irradiation1 aShetty VP1 aAntia NH00aLight and ultrastructural study of sciatic nerve lesions induced using intraneural injection of viable Mycobacterium leprae in normal and immunosuppressed Swiss white mice.  uhttp://ila.ilsl.br/pdfs/v70n1a04.pdf  a25-330 v703 a<p>Freshly harvested M. leprae were microinjected into the sciatic nerves of nonimmunosuppressed (non-TR) and immunosuppressed (TR) mice using the technique described by Wisniewski and Bloom. The lesions thus induced, on bypassing the blood-nerve barrier, were biopsied at regular intervals beginning 24 hr and followed up to one year. The fate of M. leprae and the ensuing inflammation and nerve damage were studied using light and electron microscopy. The lesions in both non-TR and TR mice at 24 hr showed an influx of polymorphonuclear leukocytes and an increase in mast cells. The influx and peaking of lymphocytes were delayed by two weeks and 6 weeks, respectively, in TR mice, but the density of lymphocytes at the peak intervals was comparable in both. The plasma cells denoting the humoral response were seen in both, but there was a delay of 3 weeks in non-TR mice. The lesions in non-TR mice showed differentiation of macrophages into epithelioid cells and the formation of giant cells depicting borderline tuberculoid leprosy (BT), Whereas in TR mice, the macrophages showed foamy cytoplasmic changes depicting borderline lepromatous leprosy (BL). Other significant observations common to both non-TR and TR mice were: a) The lesions remained highly localized and showed signs of regression at the 6th and the 12th month intervals. b) The characteristic segmental demyelination and some attempt at remyelination were seen at the site. c) The influx of lymphocytes concorded well with demyelination. d) Bacteria were only seen in the macrophages and never in the Schwann cells or endothelial cells. e) Bacteria persisted in the macrophages, but appeared progressively degenerate at the 6th and 12th post-inoculation months, suggesting loss of viability. The study shows that there was a very effective containment of the infection and that the Schwann cells were resistant to M. leprae infection in the neural milieu. Nerve damage and Schwann cell bacillation do not go hand-in-hand.</p>  a0148-916X