| Abstrakt: |
Isolated keratinocyte necrosis, often visible even on light microscopy, is the end result of target cell lysis resulting from several immune mechanisms. On electron microscopy, the keratinocyte necrosis may be distinguished by the concomitant presence or absence of an intact nuclear membrane. This morphological feature allows the deduction of the mechanism responsible for target cell damage. Thus, isolated keratinocyte necrosis with loss of integrity of the nuclear membranes, often associated with calcium deposits within the nucleus, occurs as a result of cytotoxic T-lymphocyte-mediated cytolysis. On the other hand, isolated keratinocyte necrosis with intact nuclear membranes occurs as a result of complement-mediated damage either from antibody-dependent cell-mediated cytotoxicity or from complement-based membrane attack complex per se. However, in the latter, T lymphocyte subsets are absent. In Stevens-Johnson syndrome, the intact nuclear membrane of necrotic keratinocytes suggests that complement- mediated mechanisms are involved, while the identification of lymphocytes bearing Fc receptors (leu 11b +) for immunoglobulin, implicates antibody-dependent cell-mediated mechanisms, i.e. antibody-dependent cytotoxicity, in the pathophysiology of the disease. |
