The effects of systemic recombinant interferon‐α‐2b were studied in 6 carefully selected patients with progressive multiple sclerosis. 3.0 million IU were given as daily subcutaneous injections for 6 months, 5 patients showed worsening disability, and in 4 of them new or enlarged lesions were detected in MRI. In one patient no change in disability was found; his MRI showed regressed changes. The mean progression index during the treatment was significantly higher (p < 0.02) than during the previous 2 to 3 years’ period of continuous progression. The frequency of peripheral blood natural killer (CD16 +) cells declined significantly 3 months during the treatment, but returned to the pretreatment values after termination the treatment. An increase of intrathecal IgG synthesis and oligoclonal bands was demonstrated in 4 and 3 patients, respectively. Our experience suggests that long‐term recombinant IFN‐α‐2b treatment may activate the immunological process of MS.

Local brain tumor therapy using lymphokine-activated killer (LAK) cells and recombinant interleukin-2 (rIL-2) has not proved to be effective in preliminary clinical trials. One obstacle to effective use of this therapy is ignorance about the events that follow contact of the LAK cells with glioma tissue. We used multicellular spheroids grown from human glioma cell lines as targets to study, in vitro, the effect of LAK cells against three-dimensional glioma tissue. Here we describe the ultrastructural changes in spheroids of H-2 glioma cells incubated in pellets of LAK cells for up to 24 hours. In H-2 spheroids, cellular damage was not restricted to the effector cell-target cell (effector-target) contact; it extended farther, at least partly because of nonspecific changes in the spheroid micromilieu. Formation of cytoplasmic blebs, a characteristic effect of T cells, natural killer cells, and LAK cells on single target cells, also occurs in H-2 spheroids, and it is not limited to the effector-target contact area either. These findings suggest that LAK cells release membrane-damaging agents that remain active outside the effector-target area, in the micromilieu of H-2 spheroid tissue.

The anti-tumor mechanisms of local LAK cell therapy are difficult to study in vivo. We describe a method to study in vitro the action of LAK cells against three-dimensional tumor tissue. Spherical cell aggregates (spheroids) grown from human glioma cell lines H-2 and U-251 were labeled with 51Cr and then incubated for up to 24 h with LAK cells. After the incubation, most spheroids were still macroscopically identifiable, and the measured reduction of volume did not correlate to the extent of damage. LAK cells infiltrated into spheroid tissue slowly as a frontier which explains why the specific 51Cr release was clearly slower from spheroids than corresponding single cell suspensions. The infiltrated area was at 1 to 2 h very thin but by 8 to 12 h consisted already of several cell layers. Most H-2 spheroids became totally infiltrated by 16 to 24 h whereas in U-251 spheroids the infiltration usually remained peripheral. In accordance with the different extent of infiltration, H-2 spheroids were clearly more sensitive to LAK cells than U-251 spheroids: at E/T ratio 10:1 the mean specific 51Cr release by 24 h was 63 and 36%, respectively. A single exposure to LAK cells released 51Cr from H-2 spheroids approximately 12 h but over 24 h from U-251 spheroids. The spheroid model can be used to study the infiltrative capacity and cytotoxicity of LAK cells against three-dimensional tumor tissue, and the method may help to find an optimal mode of local LAK cell therapy, i.e., proper combination of lymphokines and LAK cells, and proper timing of their administration.

The activity of lymphokine (interleukin-2) activated killer (LAK) cells from 9 patients with transitional cell carcinoma (TCC) was tested against autologous, freshly purified transitional carcinoma cells. Cytotoxicity was relatively low. Bacillus Calmette-Guérin (BCG) substantially augmented both LAK activity and the cytolytic activity of non-stimulated peripheral blood mononuclear cells (PBMC) against autologous TCC when tested with 6 additional TCC patients. A similar enhancing effect of BCG was noted with leucocytes obtained from normal donors when tested against an allogenic T24 cell line. Both natural killer (NK) cells and T cells appeared to be responsible for the increased cytolytic activity caused by BCG. No cytolytic activity was noted against normal transitional epithelial cells. Sensitisation of TCC cells to the immune system may explain the clinical effects of BCG.

Different populations of unstimulated and IL-2-activated PBL were used in binding and killing assays against somatic mouse/human lymphocyte cell hybrids containing different human chromosomes. Unstimulated PBL effector cells showed low binding and killing activity to both cell hybrids and mouse parental cell lines. However, IL-2-activated killer (LAK) cells bound strongly to, and effectively killed, cell hybrids carrying human chromosome 6, but were inefficient in both assays to mouse parental cells and to cell hybrids not carrying human chromosome 6. These results show that human LAK cells but not endogenous NK cells bind and kill mouse/human lymphocyte hybrids containing human chromosome 6. We thus suggest that LAK cells recognize ligands encoded by genes on chromosome 6.