Chemo-immunotherapy and immunological study in carcinoma of larynx and laryngopharynx

Eighteen of 25 patients had squamous cell carcinoma in the supraglottic region. Anergy to skin test antigen (DNCB) and T-cell mitogen (PHA) was observed in 17 patients with laryngeal and laryngopharyngeal malignancies. Chemo-immunotherapy did not improve the skin reactivity to either agents. However, a rise in absolute T-cell counts was observed following combined therapy. Moreover, T-lymphopenia was detected in the patient group prior to therapy as compared to mean T-cell counts in normal control subjects.

Cervical intraepithelial glandular neoplasia diagnosis and significance in relation to squamous precancerous lesions

The endocervical epithelium of histologically confirmed dysplasia and carcinoma-in-situ cases of cervix uteri was examined for the presence or absence of intraepethelial glandular Neoplasia (CIGN). Results from 80 cases were compared with equal number of controls who were being operated for reasons other than Neoplasia. In the present communication we have used the criteria of Nuclear enlargement and elongation, hyperchromasia, stratification, increased N/C ratio, pleomorphism and dence clumping to distinguish CIGN from normal endocervical epithelial lining using the criteria mentioned above we recorded CIGN in eleven cases of test group while in two of controls which implied a statistically significant (p less than .5) association of CIGN with case series as compared to controls. Among the test group; 1, 2 (15.3%), 3 (23%) and 5 (10%) cases were associated with mild, moderate, sever dysplasia and carcinoma-in-situ respectively.

Cell membrane is a major locus for ultraviolet B-induced alterations in accessory cells

In vitro ultraviolet B (UVB) irradiation of human blood monocytes inhibits their accessory cell function for antigen- and mitogen-induced T cell responses. These studies were designed to characterize the nature of the UVB-induced defect in human monocyte accessory cell function. Irradiated monocytes were deficient in their ability to serve as accessory cells for OKT3-induced T cell activation. In vitro exposure of monocytes to 100 J/m2 UVB completely inhibited the T cell proliferative response (51502 cpm, non-UVB-irradiated; 302 cpm, UVB-irradiated). Analysis of the accessory signals altered by UVB indicated that irradiated monocytes were incapable of binding to OKT3 molecules attached to the CD3 antigen on T cells. Provision of an alternative mechanism for binding of OKT3 molecules by attaching anti-mouse IgG to the bottom of microtiter wells completely restored accessory cell function. Further characterization of the defect demonstrated that UVB radiation did not deplete p72 Fc receptors from the surface of irradiated monocytes. However, UVB exposure did produce a dose-dependent decrease in monocyte membrane expression of ICAM-1. It is proposed that UVB radiation leads to changes within the cell membrane that inhibit the ability of monocytes to express selected molecules necessary for binding of T cells.

Evidence for the metabolism of tumor promoter organic hydroperoxides into free radicals by human carcinoma skin keratinocytes: an ESR-spin trapping study

Humans are exposed to various peroxy and hydroperoxy compounds which are in use in the cosmetic, pharmaceutical and polymer industries and which are also generated as a result of the peroxidative metabolic conversion of certain lipids. This study was designed to determine whether the organic hydroperoxides, tert-butyl hydroperoxide, cumene hydroperoxide and tert-butyl peroxybenzoate are metabolized by human carcinoma skin keratinocytes to free radicals. Incubation of keratinocytes prepared from cutaneous squamous cell carcinoma in phosphate-buffered saline (pH 7.4) containing desferrioxamine with tert-butyl hydroperoxide, cumene hydroperoxide and tert-butyl peroxybenzoate in the presence of spin trap (3,5-dibromonitrosobenzene sulfonic acid) resulted in the generation of corresponding methyl radical adducts. Prior heating of the cells to 100 degrees C abolished the generation of radical adducts. The addition of ethanol to the reaction mixture also inhibited formation of radical adducts. These data provide the first direct evidence that human carcinoma skin cells can generate free radicals from organic hydroperoxides. Since free radicals are suggested to be involved in the cascade of events occurring during tumor promotion this metabolic capacity may be an important determinant of human cancer risk for hydroperoxides.

Inhibition of the high affinity Fc receptor (Fc gamma RI) on human monocytes by porphyrin photosensitization is highly specific and mediated by the generation of superoxide radicals

p72 high affinity receptors (Fc gamma RI) for the Fc portion of IgG molecules on human peripheral blood monocytes mediate a variety of beneficial functions, but also have deleterious effects in certain clinical situations. In the present study, the photosensitizing porphyrins hematoporphyrin derivative and dihematoporphyrin ether (DHE), which are known to preferentially affect the cell membrane, were found to significantly inhibit binding of mouse IgG2a antibodies to the ligand binding site of Fc gamma RI on human peripheral blood monocytes and the U937 human monocytic cell line. Fc gamma RI receptors could be identified with a monoclonal antibody which recognizes an epitope distinct from the ligand binding site, indicating that photosensitization induced a structural alteration rather than loss of the receptor molecule from the cell surface. The effect of DHE and light appeared to be highly specific, since binding of monoclonal antibodies to other surface structures was not decreased. DHE plus light-induced modulation of Fc gamma RI was found to be mediated by superoxide anions, since addition of a mimic of superoxide dismutase restored both binding of mouse IgG2a to Fc gamma RI as well as human monocyte accessory cell function. These studies identify porphyrin photosensitization as a unique mechanism by which to selectively down-regulate Fc gamma RI-mediated functions.

Mechanism of action of cysteine proteinases: oxyanion binding site is not essential in the hydrolysis of specific substrates

To study the possible stabilization of the oxyanion of the tetrahedral intermediate formed in the course of the catalyses by cysteine proteinases, papain, chymopapain, papaya peptidase A, and ficin, we synthesized N-(benzyloxycarbonyl)phenylalanylthioglycine O-ethyl ester and compared its hydrolysis with that of the corresponding oxygen ester, a highly specific substrate of the above enzymes. It was found that the substitution of sulfur for the carbonyl oxygen hardly affected the second-order rate constant of acylation and diminished catalytic activity by about 1 order of magnitude in deacylation. These results contrast with those obtained with serine proteinases [Asbóth, B., & Polgár, L. (1983) Biochemistry 22, 117-122], where the hydrolysis of thiono esters could not be detected. From the results the following conclusions can be drawn. Stabilization of the tetrahedral intermediate at an oxyanion binding site is not essential with cysteine proteinases. Therefore, and because of the lack of general base catalysis, cysteine proteinases have a less constrained transition-state structure than serine proteinases.