ROLE OF NATURAL-KILLER-CELLS AND TCR-GAMMA-DELTA T-CELLS IN ACUTE AUTOIMMUNE ENCEPHALOMYELITIS

To elucidate the role of NK cells and TCR gamma delta(+) T cells in ac ute experimental autoimmune encephalomyelitis (EAE) induced in Lewis r ats, the distribution, number and function of these cells were studied using several methods. Immunohistochemical and flow cytometric analys is revealed that a certain number of NK cells (17% of the total inflam matory cells) infiltrated the central nervous system (CNS) at the peak stage of EAE and were mainly located in the perivascular region. On t he other hand, virtually no TCR gamma delta(+) T cells were found in t he CNS. NK-T (NKR-P1(+)TCR alpha beta(+)) cells were few and did not i ncrease in number in the CNS and lymphoid organs. In the cytotoxic ass ay using YAC-1 cells, effector cells isolated from the spleen of rats at the peak of EAE showed essentially the same cytotoxicity as those i solated from normal controls although the total number of NK cells dec reased to one fifth of that of normal rats. Furthermore, in vivo admin istration of anti-NK cell (3.2.3 and anti-asialo GM1), but not of anti -TCR gamma delta (V65), antibodies exacerbated the clinical features o f EAE and induced fatal EAE in some rats. These findings suggest that NK cells play a suppressive role in acute EAE whereas TCR gamma delta( +) T cells are not involved in the development of or recovery from the disease.