Determination of the immunoglobulin class of complement-dependent cytotoxic antibodies in serum of D23 hepatoma-bearing rats

Progress of Molecular Display Technology Using Saccharomyces cerevisiae to Achieve Sustainable Development Goals

In the long history of microorganism use, yeasts have been developed as hosts for producing biologically active compounds or for conventional fermentation. Since the introduction of genetic engineering, recombinant proteins have been designed and produced using yeast or bacterial cells. Yeasts have the unique property of expressing genes derived from both prokaryotes and eukaryotes. Saccharomyces cerevisiae is one of the well-studied yeasts in genetic engineering. Recently, molecular display technology, which involves a protein-producing system on the yeast cell surface, has been established. Using this technology, designed proteins can be displayed on the cell surface, and novel abilities are endowed to the host yeast strain. This review summarizes various molecular yeast display technologies and their principles and applications. Moreover, S. cerevisiae laboratory strains generated using molecular display technology for sustainable development are described. Each application of a molecular displayed yeast cell is also associated with the corresponding Sustainable Development Goals of the United Nations.

Immune response to polyvalent melanoma cell vaccine in AJCC stage III melanoma: an immunologic survival model

BACKGROUND

Our polyvalent, allogeneic melanoma cell vaccine (MCV) induces immunoglobulin M (IgM) and immunoglobulin G (IgG) class antibodies to a 90-kDa glycoprotein melanoma-associated antigen (MAA). Additionally, MCV induces delayed-type hypersensitivity (DTH) responses that we previously correlated with survival. We hypothesized that early DTH responses to MCV and early humoral responses to the 90-kDa MAA expressed on MCV cells may be predictive of overall survival. We tested this hypothesis by monitoring immunologic profiles in 59 patients with melanoma who were receiving MCV after surgical resection of regional lymph node or soft-tissue metastases.

METHODS

Blood was drawn before vaccine administration, biweekly for 6 weeks, and then monthly. DTH to MCV was recorded at 0, 2, 4, and 8 weeks of MCV therapy. Mean antibody titers during the first 6-week interval were calculated. Changes in DTH were calculated as the difference between peak and prevaccine values (delta DTH).

RESULTS

At a median follow-up of 75.6 months (range 5-138), univariate analysis assigned prognostic significance to gender (p = 0.046), lymph node involvement (p = 0.024), delta DTH (p = 0.044), mean anti-90-kDa MAA IgG (p = 0.0009), and mean anti-90-kDa MAA IgM (p = 0.0014). In multifactorial analysis, only the three immunologic variables significantly impacted survival (p = 0.046, 0.0005, and 0.0053, respectively). A mathematical model based on delta DTH and mean anti-90-kDa MAA IgG and IgM titers closely approximated the observed individual and overall survival rates.

CONCLUSIONS

The correlation between overall survival and initial humoral/cellular immune responses to MCV immunotherapy may be useful in selecting patients most likely to benefit from prolonged adjuvant immunotherapy.

Complement-dependent lysis of tumor cells by a baboon IgM antibody to a tumor-associated antigen

We developed a high-titer polyclonal antiserum to a glycoprotein tumor-associated antigen (TAA) by immunization of a baboon with the purified glycoprotein antigen. The baboon serum was fractionated into IgG and IgM components by DEAE Affi-Gel blue chromatography. The ability of the baboon IgM anti-TAA antibody to effect tumor cell lysis in the presence of complement was tested using a chromium-release assay. The baboon antibody was able to lyse melanoma target cells (20.8%-71.4% cytolysis), breast carcinoma cells (36.5%-38.9% cytolysis), and a neuroblastoma cell line (35.5% cytolysis) in the presence of complement but did not effect significant lysis of autologous lymphoblastoid cell lines (4.9% cytolysis) or peripheral blood lymphocytes from healthy volunteers (12.6% cytolysis). Cytolysis of melanoma target cells was completely inhibited by preabsorption of the IgM anti-TAA antibody with UCLA-SO-M14 (M14) cells and partially inhibited by preabsorption with several other melanoma cell lines. There was no significant inhibition of tumor cell lysis after preabsorption of the antibody with lymphoblastoid cell lines. Complement-dependent lysis of M14 targets could be blocked by addition of the purified antigen to the antibody prior to incubation with the tumor cells. Our results suggest that the glycoprotein TAA resides on the tumor cell surface and that the baboon IgM anti-TAA antibody recognizes the antigen on the cell surface and is able to fix complement and effect the lysis of the tumor cells.

Cytotoxicity of tumour-bearer serum to D23 hepatoma cells derived from solid tumours, ascites or in vitro cultures

The complement-dependent cytotoxicity of antibodies in tumour-bearer serum (TBS) from rats carrying the chemically induced D23 hepatoma was investigated. Target cells were D23 cells from solid tumours (D23sol), from ascites tumours (D23asc), or from in vitro growing cell cultures (D23cc). The D23asc and D23cc cells were not lysed when used as target cells in the assay, although they evoke cytotoxic antibodies when growing in vivo. The D23 ascites cells became susceptible to complement-dependent lysis after trypsin treatment. This was, however, not due to unmasking of target antigens, since untreated D23 ascites cells absorbed cytotoxic antibodies as efficiently as trypsinized cells. No increase in susceptibility to complement-dependent lysis was observed after trypsin treatment of D23cc cells. Absorption of cytotoxic antibodies with D23cc cells showed no or very low antigen expression on the surface of these cells. They did, however, contain the antigen(s), since 3 M KCl extracts of the D23cc cells could inhibit the complement-dependent cytotoxicity of D23sol TBS against D23sol cells. From these data it was concluded that the susceptibility of hepatoma cells for antibody-mediated complement lysis is not only correlated with antigen expression, as was the case with the in-vitro-cultivated cells, but is also dependent on increased lytic susceptibility after trypsin treatment of the cells.

The lipid nature of a tumour-associated autoantigen from a chemically induced rat hepatoma

The target antigens for the complement-dependent cytotoxic antibodies in D23 tumour-bearer serum from rats carrying the chemically induced D23 hepatoma were extractable from extranuclear membranes of tumours with chloroform/methanol. The antigenic activity, measured by inhibition of D23 TBS cytotoxicity against D23 cells, was recovered in the phospholipid-containing fraction after silica gel chromatography. Preparative thin-layer chromatography (in chloroform/methanol/0.25% CaCl2) revealed that the antigenic activity migrated similarly to phosphatidylethanolamine and cardiolipin, although these phospholipids did not cause the inhibition seen with the antigenic fractions. Phospholipase A2 digestion of the phospholipid fraction did not affect the antigenic activity nor did it after the mobility of the antigen when analysed with thin-layer chromatography. From these results it was concluded that the antigen extracted from D23 hepatoma may be of phospholipid nature, although its molecular identity remains to be established.

Tumour-associated antigens reacting with cytotoxic antibodies in serum of hepatoma-bearing rats

3M-KCl extracts of the hepatoma D23 contain antigens that inhibit the complement-dependent cytotoxicity for D23 hepatoma cells of serum from D23 tumour-bearing rats (D23 TBS). Inhibition was not due to a general anticomplementary activity of the extracts. Although a minor part (25%) of the protein of D23-KCl extract was insoluble in PBS, this part contained most of the inhibitory activity. Fractionation of the PBS-soluble material of the extract on Concanavalin A-Sepharose showed that the inhibitory activity did not bind to the lectin. Analysis of D23-KCl extracts on a Sepharose CL-4B column showed that the antigens involved in the cytotoxicity were heterogeneously distributed in the high-mol. wt region (greater than 200,000). Precipitation with 10% trichloroacetic acid (TCA) of D23 KCl extracts revealed that most of the antigenicity was insoluble in TCA. Heating of D23 KCl extracts at 100 degrees C did not affect the antigenicity. Enzyme treatment of D23 extra nuclear membranes (D23 ENP) revealed that the inhibitory activity was not sensitive to proteolytic digestion, while treatment with phospholipase A2, C or D abrogated partly the inhibitory activity. The lipid nature of the antigenicity was indicated by its solubility in organic solvents as chloroform or n-butanol.