Natural killer (NK) cells in chronic progressive multiple sclerosis patients treated with lymphoblastoid interferon.

Natural killer (NK) cell functional activity, as defined by the lysis of 51Cr-labelled K-562 cells, and number, defined phenotypically by anti-Leu-11, are significantly decreased in chronic progressive multiple sclerosis (MS) when compared to normal controls. When age- and sex-matched populations are compared, NK cell functional activity is again significantly reduced in MS compared to controls but not when compared to a control group of other medical disease (OMD). The MS group could be differentiated from the OMD group, however, when results of NK cell functional activity are combined with NK cell phenotype. With the administration of lymphoblastoid interferon daily for 6 months, NK cell activity increased significantly at 48 h and at 1 week. By 1 month, activity decreased to a level slightly above placebo treatment values. The results likely reflect interferon's enhancement of mature NK cell activity combined with a variable effect on recruitment of pre-NK cells.