Development of monoclonal antibodies reacting against mycobacterial 65 kDa heat shock protein by using recombinant truncated products

Introduction of 65 kDa Antigen ofMycobacterium tuberculosisto Cancer Cells Enhances Anti-Tumor Effect of BCG Therapy

Bacillus Calmette Guerin (BCG) immunotherapy has anti-tumorigenic effects against bladder cancer. To improve the efficacy of BCG therapy, we introduced the gene encoding the 65 kDa heat shock protein (hsp) of Mycobacterium tuberculosis into a mouse malignant melanoma cell line (B16). An expression vector harboring the 65 kDa antigen gene was transfected into B16 using Lipofectamine, then expression of the antigen was confirmed by RT-PCR and Western blotting. Several cell lines expressing 65 kDa antigen were established (B16/65 kDa). We also established a control cell line transfected with the vector alone (B16/con). All cell lines (B16, B16/con, B16/65 kDa) were injected intraperitoneally into syngeneic mice with or without BCG prior immunization and the development of tumor ascites was examined. To analyze the mechanism of the anti-tumor effect, CD4 T cells or CD8 T cells were depleted in vivo by administering the corresponding monoclonal antibody. B16/65k Da expressed the 65 kDa hsp of M. tuberculosis. The tumor growth of B16/65 kDa was slightly retarded in naive mice, but significantly inhibited by BCG. The anti-tumor effect was totally abrogated in mice deficient in CD4 T cells, suggesting that CD4 T cells are involved in this process. The 65 kDa hsp of M. tuberculosis was expressed after gene transduction in a malignant melanoma cell line and significantly enhanced the anti-tumor effect of BCG immunotherapy. CD4 T cells play an important role in this anti-tumor effect.

A Phase I Study of an Allogeneic Cell Vaccine (VACCIMEL) With GM-CSF in Melanoma Patients

We investigated whether recombinant human granulocyte-monocyte-colony-stimulating factor (rhGM-CSF) increased the immunogenicity of VACCIMEL, a vaccine consisting of 3 irradiated allogeneic melanoma cell lines. A phase I clinical trial was performed on 20 melanoma patients in stages IIB (n=2), III (n=10), and IV (n=8), who were disease free after surgery (n=16) or had minimal disease (n=4). Cohorts of 4 patients were vaccinated 4 times with VACCIMEL and bacillus Calmette Guerin (BCG) as adjuvant. Besides, the patients received placebo (group 1) or GM-CSF: 150 microg (group 2), 300 microg (group 3), 400 microg (group 4), and 600 microg (group 5) per vaccine. The combination of VACCIMEL and GM-CSF had low toxicity. Only in group 5, grade 2 thoracic pain (3/4 patients) and abdominal cramps (2/4 patients) were observed. Delayed-type hypersensitivity increased after vaccination and it was highest in group 4. Phytohemagglutinin stimulation of peripheral blood lymphocytes was analyzed in 9 patients: 4/9 had normal stimulation; 3/9 had low basal stimulation, which recovered after vaccination; and 2/9 were not stimulated. Antimelanoma antibodies preexisted in 9/19 patients; in 3/19 patients, antibodies anti-33 kd, 90 kd, and 100 kd antigens were induced by vaccination. IgG2 but not IgG1 antibodies were detected. Anti-BCG antibodies, mostly IgG2, reached the highest post/prevaccination ratio in group 4. Median serum interleukin-12 was lower in progressing patients (61.6 pg/mL) than in those without evident disease (89 pg/mL). Thus, its low toxicity and the induction of a predominantly cellular immune response suggest that the addition of 300 to 400 microg GM-CSF to VACCIMEL is useful in increasing the immune response.

T-cell receptor variable gamma chain gene expression in the interaction between rat gammadelta-type T cells and heat-shock protein 70-like molecule

We previously reported that rat T-cell receptor (TCR) Vdelta6 of T-cell hybridomas was preferentially involved in recognition of the cell surface-expressed 70 kDa rat heat-shock cognate (hsc70, a constitutively expressed member of the hsp 70 family) protein-like molecule (#067 molecule). In the present study, we analyzed usage of the TCR Vgamma family of #067-restricted T-cell hybridomas. Our data indicated that most of these hybridomas expressed transcripts of TCR Vgamma1 and/or Vgamma2. However, some of the Vgamma2 transcripts were out-of-frame, suggesting that the TCR Vgamma1 family may be important for the recognition of #067-defined molecules. TCR Vgamma1 transcripts were detected in not only #067-restricted T-cell hybridomas, but #067-non restricted ones as well. However, V-J nucleotide sequences of #067-restricted and #067-non restricted T-cell hybridomas suggested that #067-restricted T-cell hybridomas showed limited insertion of nucleotide stretch as compared with #067-non restricted ones. In terms of amino acids, only one amino acid was added in #067-restricted T-cell hybridomas, whereas two or three amino acids were added in #067-non restricted ones. These data suggest that the heterodimer of the TCR relatively short stretch form of Vgamma1 molecule and TCR Vdelta6 may participate in recognition of the #067 molecule.

70-kDa heat shock cognate protein interacts directly with the N-terminal region of the retinoblastoma gene product pRb. Identification of a novel region of pRb-mediating protein interaction

Retinoblastoma protein (pRb) functions as a tumor suppressor, and certain proteins are known to bind to pRb in the C-terminal region. Although the N-terminal region of pRb may also mediate interaction with some proteins, no such protein has been identified yet. We demonstrated previously the in vivo protein association between pRb and 73-kDa heat shock cognate protein (hsc73) in certain human tumor cell lines. In this report we analyzed the interaction between these two proteins in vitro. Our data showed that hsc73 interacts with the novel N-terminal region of pRb; that is, pRb binds directly to hsc73 and dissociates from hsc73 in an ATP-dependent manner. By using deletion mutants of cDNA encoding pRb, the hsc73 binding site of pRb was determined to be located in the region (residues 301-372) outside the so-called A pocket (residues 373-579) of this tumor suppressor protein. This finding was compatible with the fact that the adenovirus E1A oncoprotein, which is known to bind to the E2F binding pocket region of pRb, could not compete with hsc73 for the binding. Furthermore, phosphorylation of pRb by cyclin-dependent kinase inhibited the binding of pRb to hsc73. These data suggest that hsc73 may act exclusively as the molecular chaperone for nonphosphorylated pRb. As a result, hsc73 may function as a molecular stabilizer of nonphosphorylated pRb.

Heat shock proteins in the human periodontal disease process

The production of HSP by periodontopathic Gram-negative bacteria was examined by SDS-PAGE, two dimensional gel electrophoresis, and Western blotting using monoclonal antibodies against HSPs. Strains of Actinobacillus actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum, Prevotella intermedia, Prevotella nigrescens, Prevotella melaninogenica, and Treponema socranskii species produced HSP which reacted with anti-Yersinia enterocolitica HSP 60 and/or mycobacterial 65-kDA HSP monoclonal antibodies. It found that gingival homogenate samples from patients with adult periodontitis reacted with anti-human HSP were also found in a serum sample from a periodontitis patient. The present study suggests that HSPs are implicated in human periodontal disease process.

Monoclonal antibody specifically reacting against 73-kilodalton heat shock cognate protein: possible expression on mammalian cell surface

The heat shock proteins (hsp) are regarded as being immunogenic to the animal hosts. Although certain hsp are suggested to be expressed on the cell surface, further evidence for the cell surface expression of these proteins has been required. In this article we report the development of a MAb NT22. This antibody reacted with ATP-binding proteins (which contain a large amount of 70-kDa hsp family) of HeLa cells, and with purified bovine 70-kDa hsp. It did not react with the E. coli lysate, but clearly reacted with the recombinant rat hsc73. However, NT22 failed to react with hsp72. Furthermore, stress treatment of cells also indicated that considerable amounts of NT22-defined antigen translocated into the nucleus from the cell cytoplasm. These results suggest that NT22 is a novel MAb that reacts specifically to the mammalian hsc73. Moreover, this antibody could detect the constitutive and stress-induced cell surface expression of its relevant antigen. It is expressed preferentially on EBV-transformed B cell and certain epithelial cancer cell lines. However, resting B cells did not express this antigen on the cell surface. These data indicate that hsc73 could be expressed on the cell surface of certain cells, and suggest that hsc73 may interact with the host immune system.

Demonstration of selective protein complexes of p53 with 73 kDa heat shock cognate protein, but not with 72 kDa heat shock protein in human tumor cells

It has been demonstrated that p53, especially, mutant p53 (mp53), makes protein complexes with major heat shock proteins hsp72/hsc73. However, there is no direct evidence showing whether hsp72 or hsc73 could bind preferentially to p53. In the present study, using TYKnu human ovarial carcinoma cells and monoclonal antibodies reacting specifically to hsp72/hsc73, we were able to find the selective protein complex formation with p53, presumably mp53, and hsc73, but not in the case of p53 and hsp72. The p53-hsc73 protein complexes dissociate with the addition of ATP, indicating that the dissociation is dependent upon the ATP-hydrolysis. These data suggest that hsc73 rather than hsp72 plays an important role in the yet undefined mechanism of disregulated cell growth control by mp53.

Stress proteins in aquatic organisms: an environmental perspective

The cellular stress response protects organisms from damage resulting from exposure to a wide variety of stressors, including elevated temperatures, ultraviolet (UV) light, trace metals, and xenobiotics. The stress response entails the rapid synthesis of a suite of proteins referred to as stress proteins, or heat-shock proteins, upon exposure to adverse environmental conditions. These proteins are highly conserved and have been found in organisms as diverse as bacteria, molluscs, and humans. In this review, we discuss the stress response in aquatic organisms from an environmental perspective. Our current understanding of the cellular functions of stress proteins is examined within the context of their role in repair and protection from environmentally induced damage, acquired tolerance, and environmental adaptation. The tissue specificity of the response and its significance relative to target organ toxicity also are addressed. In addition, the usefulness of using the stress response as a diagnostic in environmental toxicology is evaluated. From the studies discussed in this review, it is apparent that stress proteins are involved in organismal adaptation to both natural and anthropogenic environmental stress, and that further research using this focus will make important contributions to both environmental physiology and ecotoxicology.