Role of matrix ß-1,3 glucan in antifungal resistance of non-albicans Candida biofilms.

Candida biofilm infections pose an increasing threat in the health care setting due to the drug resistance associated with this lifestyle. Several mechanisms underlie the resistance phenomenon. In Candida albicans, one mechanism involves drug impedance by the biofilm matrix linked to ß-1,3 glucan. Here, we show this is important for other Candida spp. We identified ß-1,3 glucan in the matrix, found that the matrix sequesters antifungal drug, and enhanced antifungal susceptibility with matrix ß-1,3 glucan hydrolysis.

A viral long terminal repeat in the interleukin 2 gene of a cell line that constitutively produces interleukin 2.

The gibbon leukemia cell line MLA 144 differs from every other T-lymphocyte line in that it constitutively makes interleukin 2 (IL-2) (also called T-cell growth factor) without stimulation by antigen, lectin, or tumor promoters. Previous work in which glucocorticoids were used to inhibit IL-2 production has indicated that proliferation of this cell line is dependent upon endogenously produced IL-2. We have found that the MLA 144 cell line has a copy of the gibbon leukemia virus inserted into the 3' nontranslated region of the IL-2 gene. This integration event produces a composite mRNA made up of the protein coding sequences of the IL-2 gene transcript but incorporating the viral long terminal repeat (LTR) in the 3' nontranslated region of the mRNA. This composite mRNA transcript uses the polyadenylylation signal in the viral 5' LTR and incorporates the viral transcriptional control regions. The integration event must involve only one allele of the IL-2 gene, since transcripts essentially identical to normal human IL-2 mRNA are also produced in cloned sublines of MLA 144. That the viral LTR contains a 94-base-pair repeat reminiscent of enhancer sequences in several viruses suggests that the integration of the viral LTR at the 3' end of the IL-2 gene is responsible for the constitutive production of IL-2 in the MLA 144 cell line.

A variant translocation places the lambda immunoglobulin genes 3' to the c-myc oncogene in Burkitt's lymphoma.

Most translocations that occur in Burkitt's lymphoma involve movement of part of chromosome 8, containing the c-myc gene, from its normal position to the immunoglobulin heavy-chain locus on chromosome 14. The genes are often joined at their 5' ends in opposite transcriptional directions. However, a significant minority of Burkitt translocations involve the light-chain loci on chromosome 2 (kappa) or 22 (lambda). We have characterized one of these from a European-derived cell line (IARC-BL37) that carries an 8;22 translocation. Here the translocation has joined the 5' portion of the lambda light-chain locus to the 3' portion of the c-myc gene at a position about 7 kilobases from the normal c-myc promoters. The translocation is reciprocal and relatively conservative, involving the loss of only 21 base pairs from the site of recombination. This translocation allows us to orient the lambda genes with respect to the centromere of chromosome 22 and to predict the orientation of other translocations involving these chromosomal segments. The 3' translocation is accompanied by an increased level of c-myc transcripts, especially that derived from a normally under-used c-myc promoter.

The effect of translocations on the cellular myc gene in Burkitt lymphomas.

Chromosomal translocations are found to be a characteristic feature of Burkitt lymphomas. Similar translocations are found in mouse plasmacytomas and both diseases involve interchanges between one of the immunoglobulin loci and DNA in the vicinity of the myc gene. The structure of the myc gene has been elucidated from studies on translocated versions of the gene. Activation of the myc gene may play a role in transformation by promoting growth of the cells bearing the rearranged chromosomes.

HLA-DR histocompatibility leukocyte antigens permit cultured human melanoma cells from early but not advanced disease to stimulate autologous lymphocytes.

HLA-DR histocompatibility antigens are commonly expressed by the melanocytes of melanoma and its precursors, but not by the melanocyte of normal skin. Further, the primary lesion of biologically early melanoma is commonly infiltrated with host T cells. Advanced disease is characterized by a paucity of such cells. To investigate the interaction of melanoma cells and autologous lymphocytes and its dependence on HLA-DR expression, we have established cell lines from biologically early (4 lines) and advanced disease (11 lines) and examined their capacity to stimulate blastogenesis of autologous T cells in vitro. Melanocytes from early disease expressed HLA-DR antigens and stimulated autologous T cells. Those from advanced disease, irrespective of DR expression, were nonstimulatory. To determine whether expression of DR was required for melanoma cells to be stimulatory, we first treated a stimulating cell line of DR3 allospecificity with anti-DR3-specific serum and demonstrated marked inhibition of its capacity to provoke blastogenesis. Next we used fluorescence-activated flow cytometry to sort a stimulating line heterogeneous for DR expression into DR-enriched and -depleted populations. When such cells were examined in the lymphocyte proliferation assay, their stimulatory capacity was proportional to their quantitative expression of HLA-DR. These studies indicate that cell lines may reflect important biological differences between early and advanced melanoma. HLA-DR expression may be an early event in neoplasia of melanocytes. These antigens are able to interact directly with autologous T cells; and their expression is necessary, but not sufficient, for melanoma cells to induce lymphocyte proliferation.

DR antigens on melanoma cells: analysis with monoclonal antibodies.

Two monoclonal antibodies (691-13-17 and 37-7) can precipitate DR antigens from radioiodinated, detergent solubilized melanoma cells. However, after complete depletion of lysates with one antibody (691-13-17) alpha-like chains can be still be precipitated from some melanoma cells by the other antibody (37-7). Antibody 37-7 also precipitates an additional distinct antigen from SK-MEL 37 but not from any five other melanoma cell lines.

Identification and isolation of melanoma-associated antigens with monoclonal antibodies.

The monoclonal antibodies distributed at the first Workshop on Monoclonal Antibodies to Melanoma have been tested by immunoprecipitation, and one group of antigens (90 kd) has been found to be identical by sequential immunoprecipitation. These results are in good agreement with those from other laboratories. In addition, antigens from a new group of hybridomas, generated since the first Workshop, were studied. Some of these antigens are unique and others are duplicates of the original set. Finally, a melanoma-associated antigen (260 kd) was purified by immunoaffinity chromatography.

Monoclonal antibody-defined human lung cell surface protein antigens.

Monoclonal antibodies were used to define four distinct antigens present on the surface of human lung tumors. Immunoprecipitation of the four antigens by monoclonal antibodies and sodium dodecyl sulfate:polyacrylamide gel electrophoresis reveals that they have distinct complex structures. Different patterns of expression of these antigens on cells of other than lung tumor origin were detected by the same panel of monoclonal antibodies.

A monosialoganglioside is a monoclonal antibody-defined antigen of colon carcinoma.

The antigen of a monoclonal antibody that is specific for cells of human carcinoma of the colon is a monosialoganglioside as determined by the direct binding of antibody to thin-layer chromatograms of total lipid extracts of tissues. Binding of antibody to chromatograms is detected by autoradiography after the application of iodine-125-labeled F(ab')2 of rabbit immunoglobulin G antibodies to mouse immunoglobulins.

Biochemical characterization of human melanoma cell surfaces: dissection with monoclonal antibodies.

This report describes the structures of three distinct human melanoma surface antigens detected by monoclonal anti-melanoma antibodies. One antigen, expressed on all melanoma cells and on certain astrocytoma cells but not on any other kind of normal or tumor cell tested, has been shown to consist of our associated polypeptide chains. A second antigen expressed on many but not all melanomas has been identified as the antigenic product of the HLA-D locus, the DR antigen. A third protein antigen is not found on any normal cell tested but occurs on some, but not all, tumors of various origins.

Antibody-directed cytotoxic agents: use of monoclonal antibody to direct the action of toxin A chains to colorectal carcinoma cells.

We have constructed cell-specific cytotoxic agens by covalently coupling the A chain from diphtheria toxin or ricin toxin to monoclonal antibody directed against a colorectal carcinoma tumor-associated antigen. Antibody 1083-17-1A was modified by attachment of 3-(2-pyridyldithio)propionyl or cystaminyl groups and then treated with reduced A chain to give disulfide-linked conjugates that retained the original binding specificity of the antibody moiety. the conjugates showed cytotoxic activity for colorectal carcinoma cells in culture, but were not toxic in the same concentration range for a variety of cell lines that lacked the antigen. Under defined conditions virtually 100% of antigen-bearing cultured cells were killed, whereas cells that lacked the antigen were not affected. Conjugates containing toxin A chains coupled to monoclonal antibodies may be useful in studying functions of various cell surface components and, possibly, as tumor-specific therapeutic agents.

Rat cell surface antigens: Nonidentity of the H-4 and Ag-F traits.

Animals partially congenic to Lewis have been bred that differ at the locus, linked to C., which controls the Ag-F antigenic trait. Skin grafts from these animals, placed on Lewis recipients, were not rejected. This result demonstrates that Ag-F does not mediate skin incompatibility and, thus, is distinct from H-4, which was defined based on a demonstrable incompatibility and which is also linked to C.