Natural killer cell activity in hepatocellular carcinoma. In vitro and in vivo responses to interferon

We have measured natural killer (NK) cell activity in patients with hepatocellular carcinoma (HCC) and have examined the effects of in vitro and in vivo administration of alpha-interferon (IFN) on NK cell activity. The NK cell cytotoxicity of HCC patients was significantly lower than that of patients with cirrhosis or healthy controls. Reduced NK cell cytotoxicity in HCC did not correlate significantly with either the serum alpha-foetoprotein concentration or the patient WHO performance grade. NK cell cytotoxicity in all groups could be increased by prior incubation of effector cells with IFN, but this was significant only in HCC patients, in whom 10 IU/ml of IFN increased NK cell cytotoxicity from 37 +/- 10% to 53 +/- 8% (effector to target ratio, 50:1, mean +/- SEM; p less than 0.05). Further increases in IFN concentration failed to increase NK cell activity further. NK cell cytotoxicity was measured immediately before and 24 h after 2.5 x 10(6) IU/m2 of IFN was given subcutaneously to four HCC patients. NK cell cytotoxicity rose from 27 +/- 9% to 61 +/- 5% (effector to target ratio, 50:1, mean +/- SEM; p = 0.05).

HLA class I and II, interferon, interleukin 2, and the interleukin 2 receptor expression on labial biopsy specimens from patients with Sjögren's syndrome

Labial biopsy specimens from eight patients with primary Sjögren's syndrome (SS), 10 patients with secondary SS, and three healthy controls were studied with monoclonal antibodies identifying HLA class I and class II antigens; interferon-alpha, beta, and gamma; interleukin 2 (IL2); and the IL2 receptor (Tac) among others. In the normal biopsy specimens there was evidence of HLA class I and, to a lesser extent, class II antigens in both ducts and acini, though this was much less marked than in the Sjögren's biopsy specimens. Interferon-gamma staining, but not interferon-alpha or beta, was also considerably enhanced in the biopsy specimens from the patients with Sjögren's syndrome. These data support the view that in Sjögren's syndrome the release of interferon-gamma may be involved in the induction of class II determinants. Our observations were broadly similar in both primary and secondary Sjögren's syndrome except that patients with primary Sjögren's syndrome tended to have more diffusely scattered T lymphocytes.

The human interferon-gamma receptor. Purification, characterization, and preparation of antibodies

The receptor for human interferon-gamma (IFN-gamma) was purified from foreskin fibroblasts. Triton X-100 extracts obtained from either intact cells or membrane preparations were passed through an immobilized interferon-gamma column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of eluted fractions revealed a major band of Mr = 95,000 and minor bands of Mr = 80,000 and 60,000. Further purification was obtained by steric exclusion and by lectin chromatography. The purified receptor retained the ability to bind 125I-IFN-gamma with a Kd of 2.2 X 10(-10) M, a value close to that obtained with intact fibroblasts (5 X 10(-10) M). A complex of Mr = 105,000-125,000 was visualized by immunoprecipitation of 125I-IFN-gamma cross-linked to the purified receptor followed by SDS-PAGE and autoradiography. A similar complex was obtained when 125I-IFN-gamma was cross-linked to intact cells. Immunization of mice with the excised SDS-PAGE band of Mr = 95,000 elicited antibodies that blocked the antiviral activity of IFN-gamma and immunoprecipitated the cross-linked complex of 125I-IFN-gamma and its receptor.

Efficient constitutive production of human IFN-gamma in Chinese hamster ovary cells

A human genomic DNA segment of 5.6 kb containing the entire gene for immune interferon-gamma was fused through its 5'-untranslated region to the corresponding region of the simian virus 40 (SV40) T-antigen gene. The SV40 early promoter used contained a modified transcriptional enhancer element with a 93-bp repeat. Supercoiled plasmid DNA was used to transfect Chinese hamster ovary (CHO) cells, the selectable marker being a SV40-dihydrofolate gene construct. Constitutive expression of the IFN-gamma gene in primary transformants was high, especially if a Harvey murine sarcoma virus long terminal repeat (LTR) was present in addition to the SV40 promoter. After gene amplification by methotrexate selection, CHO-gamma cell lines were obtained that produce 1.5-2 million units of IFN-gamma per million cells and per day (200,000 molecules per cell per minute). Metabolic labeling showed that over 90% of the protein secreted by such cells is human IFN-gamma. A one-step immuno-affinity chromatography on monoclonal antibodies yielded pure IFN-gamma with 1-2 X 10(8) units/mg protein. Like IFN-gamma from human white blood cells, the IFN-gamma from CHO-gamma cells is a mixture of two glycoproteins of 26,000 and 20,000 daltons with traces of the unglycosylated 17,000-dalton polypeptide. Large-scale cultures in 1% serum routinely yield over 600,000 units of human IFN-gamma/ml culture per day.

Localization of interferons and interleukin 2 in polymyositis and muscular dystrophy

Muscle biopsies from nine patients with polymyositis, six with muscular dystrophy, six with other muscle diseases and three controls have been studied with a panel of 10 monoclonal antibodies (MoAb) identifying T lymphocytes, HLA-class I antigens, alpha, beta and gamma interferons and interleukin 2 (IL-2). The result confirm that the staining of the sarcolemma with anti-HLA class I antibody is weak or negative, except in areas adjacent to infiltrating leucocytes or where muscle fibre damage is evident. The very similar tissue distribution of alpha, beta and gamma interferons in the polymyositis biopsies supports the hypothesis that interferons are released by the inflammatory infiltrate and induce the class I antigen expression. In contrast, little interferon was demonstrated in the dystrophic muscle implying that class I expression in these disorders must occur by a different mechanism. Little IL-2 was demonstrated in any of the biopsies though some unexplained small dense accumulations were identified by one of the anti IL-2 MoAb.

Efficient constitutive production of human fibroblast interferon by hamster cells transformed with the IFN-beta 1 gene fused to an SV40 early promoter

The coding sequence of the human interferon (IFN)-beta 1 gene, fused 60 bp downstream from the RNA start site of the SV40 early gene, was transfected into dihydrofolate reductase (DHFR)-deficient Chinese hamster ovary (CHO) cells together with a selectable DHFR gene. Most transformants continuously secreted IFN-beta 1 into the medium. Induction did not stimulate expression of the fused SV40-IFN-beta 1 gene. The role of the SV40 promoter was verified by transforming cells with the unmodified human IFN-beta 1 gene, or by the IFN-beta 1 coding region fused to another poly(rI):(rC)-inducible gene. In these cases, the transformants showed strictly inducible (not constitutive) IFN secretion. By selection for methotrexate resistance, CHO clones with a 10-20-fold amplification of the SV40-IFN-beta 1 DNA were obtained. Such clones constitutively produce up to 350,000 units IFN/ml per 10(6) cells/24 hr, i.e., over 10 times more than fully induced human fibroblasts. In continuous culture with daily changes of medium, accumulation of IFN-beta 1 is constant at a rate of 300,000 molecules per cell/hr. Batches of up to 16 mg of IFN-beta 1 produced by the transformed CHO cells were purified to homogeneity by affinity chromatography on monoclonal antibodies. This IFN appears identical in size, activity, and immunospecificity to the native human IFN-beta 1 glycoprotein.

Type I and Type II interferon receptors

Binding site competition studies of 125I-interferon (IFN)-gamma were performed with homogeneous preparations of IFNs alpha 2, beta, and gamma. It was found that only IFN-gamma could compete for the specific binding site of 125I-IFN-gamma in both WISH and FS11 cells. Thus, a clear distinction between the receptor of IFN- alpha and beta on one hand, and the receptor of IFN-gamma on the other hand, was obtained. This result is unambiguous because all IFN preparations which were used were purified to homogeneity by specific monoclonal antibody immunoaffinity chromatography. We propose to assign the names "Type I" for the receptor of IFN-alpha and IFN-beta, and "Type II" for the specific receptor of IFN-gamma.

Affinity chromatography of human fibroblast interferon (IFN-beta 1) by monoclonal antibody columns

Eight hybridomas secreting monoclonal antibodies specific to human fibroblast interferon (IFN-beta 1) were identified by a new screening procedure based on immune precipitation with a second antibody and recovery of interferon activity from the immune precipitate. Immunoadsorbents were prepared from these monoclonal antibodies and used for purification of IFN-beta 1. Electrophoretically pure IFN-beta 1, having a specific activity of 3 X 10(8) to 6 X 10(8) units/mg was obtained by a single passage of partially purified IFN-beta 1 on these immunoadsorbents.

Monoclonal antibodies to human alpha-interferon and their use for affinity chromatography

A new screening procedure has been developed and used for the identification of three hybridomas secreting monoclonal antibodies to human leukocyte interferon (IFN-alpha). The screening procedure is based on immune precipitation with a second antibody, acid dissociation of the precipitate, and bioassay of the recovered interferon. This procedure selects for monoclonal antibodies that are suitable for affinity chromatography, as demonstrated by construction of immunoadsorbents from these monoclonal antibodies and purification to homogeneity in IFN-alpha.

Monoclonal antibodies to human alpha-interferon and their use for affinity chromatography

A new screening procedure has been developed and used for the identification of three hybridomas secreting monoclonal antibodies to human leukocyte interferon (IFN-alpha). The screening procedure is based on immune precipitation with a second antibody, acid dissociation of the precipitate, and bioassay of the recovered interferon. This procedure selects for monoclonal antibodies that are suitable for affinity chromatography, as demonstrated by construction of immunoadsorbents from these monoclonal antibodies and purification to homogeneity in IFN-alpha.

Immune regulation of experimental myasthenia

Experimental autoimmune myasthenia gravis (EAMG) is an appropriate model for studying the molecular origin, immunological mechanism and regulation of myasthenia gravis. Several approaches are being utilised for the regulation of the immune response to AChR and for immunosuppression of EAMG: Corticosteriods and azathioprine can suppress EAMG concomitantly with suppression of immune responses to AChR. High dose cyclophosphamide treatment in mice facilitates the onset of EAMG and results in a selective suppression of the humoral response to AChR whereas the cellular response is enhanced. Specific immunosuppression of EAMG is achieved by using a nonmyasthenic, denatured AChR preparation which cross reacts with the intact receptor. Various degradations and modifications of AChR are being performed in order to identify the smallest molecular entity responsible for the myasthenic activity of AChR. Studies on specific monoclonal antibodies, anti-idiotypes, and on the effect of measles virus on EAMG are being described and their possible significance in regulating myasthenia are being discussed.