The K562 tumor cell is a highly susceptible target for natural killer (NK) cell lysis by
the lymphocytes of human peripheral blood. In an experiment with blood samples of
leprosy patients, the natural killer cell mediated cytotoxicity (NKMC) against
51Cr-K562 as a target cell was studied in 39 leprosy patients (12 with
lepromatous type, 11 with tuberculoid type and 16 with borderline group) and 11 normal
controls.
In a comparison between the effector/target cells ratio as 50 : 1, the NKMC was seen
to be more significantly reduced in lepromatous and borderline leprosy (mean±S.D. ;
24.9±4.9, 28.5±8.6) than those in normal controls (mean±S.D. ; 39.2±13.3). In the cases
of lepromatous, it was significantly reduced compared to tuberculoid leprosy (mean±S.D.
: 34.5±7.6), but in tuberculoid leprosy, NKMC was not much lower than in normal
subjects.
A possible explanation for the low NK cell activity in lepromatous patients could be
the blocking of such activity by immune complexes. It does, however, indicate a useful
role for the NK system as an additional parameter for the evaluation of cell mediated
immunity (CMI) and as a prognostic monitoring tool in leprosy.
|