Intensity of class I antigen expression on human tumour cell lines and its relevance to the efficiency of non-MHC-restricted killing

Abstract

Summary A modified tetrazolium reduction assay (MTT) was used to assess the relation between HLA class I antigen expression on tumour cells and their susceptibility as a target for non-MHC restricted LAK/NK cytotoxicity using interleukin-2 activated peripheral blood mononuclear cells (MNC) from normal individuals. At 20/1 effector/target ratio this ranged from no killing to 77%. The efficiency of killing was dependent on duration of effector cell culture with IL-2, peaking at day 10 and declining thereafter. This killing could be enhanced by addition of other cytokines including interferons alpha, beta and gamma.Study of a panel of 15 tumour cell lines using a single effector showed that there was no statistically significant inverse correlation (using Spearman rank test) between the degree of tumour class I expression and LAK/NK killing at 20/1 (r = 0.23 P = 0.39) and 10/1 (r = 0.30, P = 0.27) and at 5/1 E/T ratio r = 0.47, P = 0.08) respectively. Lack of inverse correlation between these two parameters came from study of one bladder tumour line (FEN), whose absent class I antigens had been corrected by transfection with P2 microglobulin gene. At high E/T ratio (20/1) there was an increase in the susceptibility of target cells to lysis (36% parent cell, 45% transfected cell), whilst at lower E/T ratios (1/1) there was significantly more killing of the non-transfected cells (10% vs 31%). The addition of anti-class I antibody W6/32 increased killing by 18% but this was non-specific as the same increase occurred with a class II antibody.These data suggest that overall there was not an inverse correlation between class I expression and LAK/NK killing at high E/T ratios, whilst at low (5/1 or lower) E/T ratios this correlation nearly reached statistical significance suggesting that the conflicing literature reports may be due to a threshold levels of effector cells above which the masking effects of MHC antigens disappears.

Adenovirus-mediated interleukin-12 gene therapy for prostate cancer: suppression of orthotopic tumor growth and pre-established lung metastases in an orthotopic model

“…This leads to the production of IFN-␥ by NK cells, and increased cytotoxic activity of NK cells against tumor cells with low MHC class I expression. 28,29 The cytotoxic activity may be the result of perforin-mediated lysis independent of the production of IFN-␥. 30 In the present study, increased NK activity was documented by YAC cell lysis assays with splenocytes with a maximum on day 1 and persistence to day 3 after IL-12 gene therapy.…”

Profile of Placental Alkaline Phosphatase Expression in Human Malignancies: Effect of Tumour Cell Activation on Alkaline Phosphatase Expression

“…The tumour cell lines Fen and Wil were established in our laboratory from patients with superficial bladder cancers [19]. Other cell lines used including SKV14 (SV40-transformed foreskin epithelial line), MCF7 (breast), T47D (breast), Tera I (testis), Tera II (testis), Ep2102 (testis), Jar (testis), Ish (endometrial), Hep2 (oral), KB (oral), HeLa (cervical carcinoma), A431 (vulva) and BeWo (testis) were obtained from the ECACC and the American Type Culture Collection (ATCC).…”

Comparison of Immunological Changes between Subcutaneous and Intravenous Route of Administration of IL-2 in Cancer Patients

“…This would imply that by losing class I antigens, whilst the tumour cells become less visible to MHC-mediated CTL killing, they become more vulnerable to cytotoxicity by the non-specific killer cells, i.e., natural killer cells, leading one to expect more frequent responders cases, particularly, since IL-2 is a well-documented activating signal for induction of natu ral killer activity [6], To address this discrepancy, Storkus et al [13] have put forward yet another complexity, suggesting that not all the polymorphic class I determinants expressed on tumour cells exert the same degree of influence on the induction of natural killer activity. They implied that although there are frequent abnormalities in the expres sion of MHC antigens on human tumours, these abnor malities are frequently polymorphic and may not in fluence the induction of non-specific natural killing.…”