Karel Raska

Impact of Perceived Self-Efficacy in Coping With Stressors on Components of the Immune System

This experiment examined the impact of experimentally varied perceived self-efficacy in exercising control over stressors on components of the immunological system. Immunological changes while coping with phobic stressors were measured within an intrasubject control design that included a baseline phase, an efficacy-acquisition phase, and a maximal-efficacy phase. In each of these phases, perceived coping self-efficacy, level of autonomic and endocrine activation, and several components of the immunological system were measured. Development of strong perceived self-efficacy to control phobic stressors had an immunoenhancing effect. A slow growth of perceived self-efficacy, heart rate acceleration, and cortisol activation attenuated immunological system status during the efficacy-acquisition phase. Rapid growth of perceived self-efficacy also predicted maintenance of immunoenhancement during the maximal perceived self-efficacy phase.

Does the synthesis of ribosomal RNA take place-within nucleolar fibrillar centers or dense fibrillar components?

By means of immunocytochemistry performed on cryosections of cultured cells, RNA polymerase I was localized mainly to nucleolae fibrillar centers. The labelling of nucleolar dense fibrillar components was low and depended on the cell type. In contrast, DNA topoisomerase I and RNP complexes containing U3 snRNA were enriched in dense fibrillar components, their occurrence in fibrillar centers being usually much less.

An inverse relation of the oncogenic potential of adenovirus-transformed cells and their sensitivity to killing by syngeneic natural killer cells

Abstract Sensitivity of five adenovirus (Ad) -transformed cell lines to killing by syngeneic natural killer (NK) and secondary cytolytic T cells has been studied. The transformed cell lines have different oncogenic potentials in vivo : A 2 T 8 cells are nontumorigenic even in immunosuppressed newborn animals; T 2 C 4 cells induce tumors in immunosuppressed but not in untreated newborn rats; 50A cells are tumorigenic in newborn rats; RFC 1 and RT 2 cells are highly oncogenic in both newborn and in weanling rats and induce tumors after intraperitoneal injection to mature rats. The results show an inverse relation between the sensitivity of these cells to NK cytotoxicity in vitro and their tumorigenic potential in vivo . Competition experiments and adsorptions of effector cells to monolayers of target cells indicate that antigenic specificities on all five tested adenovirus-transformed cells are recognized by the same subset of NK cells. In parallel experiments no significant differences were detected in sensitivity of these transformed cell lines to killing with syngeneic secondary cytolytic T cells. The T-cell killing was highly specific for Ad2- or Ad12-transformed cells, respectively. In vitro education of secondary cytolytic T cells in this system is not associated with generation of NK activity. These results suggest that sensitivity of different Ad-transformed cells to killing by natural cell-mediated cytotoxicity, rather than their immunogenicity, correlates with their oncogenic potential.

Tumorigenicity of adenovirus-transformed cells: Region E1A of adenovirus 12 confers resistance to natural killer cells

Sensitivity of a library of rat cells transformed in vitro with viable recombinant adenoviruses to natural killer (NK) cells and allogeneic cytotoxic T cells has been studied and correlated with their oncogenic potential in syngeneic rats. All cell lines transformed with the sub370-12E1AB virus (containing E1A and E1B regions of Ad12) and with the sub370-12E1A virions (containing the E1A region of Ad12 and the E1B region of Ad5) showed a high degree of resistance to NK cells. The cell lines transformed with the sub370-12E1B virus (containing the E1A region of Ad5 and the E1B region of Ad12) were highly sensitive to NK cytotoxicity. While all cell lines transformed with virions containing the E1A genes of Ad5 expressed high levels of class I MHC antigen, only three of eight cell lines containing the E1A region of Ad12 showed detectable levels by flow cytometric analysis after staining with specific antibodies. All cell lines containing E1A genes of Ad5 were killed by in vitro generated allogeneic cytolytic T cells. Only three of eight cell lines containing the E1A region of Ad12 were killed by such CTLs; the level of cytotoxicity, however, did not reach that seen with the cells containing the E1A genes of Ad5. All cell lines containing the E1A and E1B genes of Ad12 were highly tumorigenic. Only two of four cell lines transformed with virus containing the E1A genes of Ad12 and E1B region of Ad5 were tumorigenic. The efficiency of tumor induction was low and the latent period was long confirming the importance of the E1B region. None of the cell lines transformed with virus containing the E1A region of Ad5 and the E1B genes of Ad12 were tumorigenic, reflecting their high degree of sensitivity to both natural and induced cellular immunity. Expression of the E1A region of Ad12 in transformed cells modulates not only the level of class I MHC antigens, but also confers resistance to NK cell cytotoxicity.

Tumorigenicity of adenovirus-transformed rat cells and expression of class I major histocompatibility antigen

The expression of class I major histocompatibility antigens was studied in six syngeneic adenovirus 12 (Ad12)-transformed LIS rat cell lines of varying tumorigenicity. The concentration of MHC class I product was estimated by indirect immunofluorescence staining of viable cells in suspension with specific antibody and cytofluorographic analysis, and by sensitivity to killing by allogeneic cytolytic T cells (CTLs) elicited by immunization with spleen cells in vivo and in mixed lymphocyte reactions in vitro. None of the rat cell lines examined was devoid of MHC class I antigen. When compared to syngeneic Ad2-transformed cells or fibroblasts, the average intensity of fluorescence of Ad12-transformed lines was lower, suggesting that the concentration of MHC class I antigen is somewhat lower in Ad12-transformed cells. Sensitivity to killing by both in vivo and in vitro induced allogeneic CTLs, however, was not markedly lower with Ad12-transformed cells and correlation was not found between tumorigenic potential in vivo and sensitivity to allogeneic T-cell killing in vitro.

Suppressor cells in end-stage renal disease: Functional assays and monoclonal antibody analysis

Suppressor cell activity after concanavalin A induction was studied in peripheral blood mononuclear cells of patients undergoing long-term hemodialysis. Suppression both of the mixed lymphocyte reaction and of allogeneic cells stimulated with phytohemagglutinin was significantly higher with peripheral blood mononuclear cells from patients undergoing hemodialysis than with cells from control subjects. Expression of the Ia antigen on T lymphocytes (associated with immunologic activation) was studied by staining with monoclonal antibodies and two-color fluorescence analysis in a computer-linked cytofluorograph. In unstimulated cells, there was no significant difference between the patients and control subjects. After concanavalin A induction, the percentage of T4, and particularly of T8, cells expressing the Ia antigen was significantly higher in the group undergoing hemodialysis. The functional suppression seen after concanavalin A induction in the mixed lymphocyte reaction was significantly reduced by treatment with OKT8 monoclonal antibody and complement; in phytohemagglutinin cultures, both OKT8 and OKIa*1 antibodies were effective. The reduced in vitro response of uremic lymphocytes may thus be a consequence of increased suppressor activity associated with the T8-positive, Ia-positive subset of T cells.

Human immunodeficiency virus infection in sexually active wives of infected hemophilic men

PURPOSE Because of past multiple exposures to contaminated coagulation factor concentrates, the prevalence of human immunodeficiency virus (HIV) infection among adult hemophilic men in the United States is reported to range from 75 to 90 percent. The risk of HIV transmission through a long-term monogamous heterosexual contact can be estimated by studying the spouses of hemophilic subjects since these couples generally do not abuse intravenous drugs, usually maintain stable monogamous relationships, and are usually free of other risk factors. Our purpose was to gather data on the risk of heterosexual transmission of HIV infection in the context of long-term monogamous relations according to the duration of HIV antibody seropositivity and of HIV antigenemia in HIV-infected hemophilic men, and their sexual habits. SUBJECTS AND METHODS Infection with HIV was studied in 14 sexually active spouses of infected hemophilic men who had been HIV antibody reactive for a mean of 46 +/- 23 (SD) months. One half of the hemophilic men studied had overt HIV antigenemia for a mean duration of 27 +/- 23 (SD) months; six of the men studied fulfilled clinical criteria for the diagnosis of acquired immunodeficiency syndrome (AIDS). All 14 couples were sexually active in a strictly monogamous fashion, in marriages of 13.5 +/- 10.5 (SD) years with an average reported frequency of four sexual encounters per month (range: one to 12). Plasma samples of the hemophilic husbands were retrospectively analyzed for HIV and hepatitis B virus markers. Blood samples were obtained from female spouses on at least two occasions, six months apart. Comprehensive questionnaires regarding sexual habits and other risk factors were filled out by each couple; during this interview, the couple was counseled about safe sexual practices. None of the couples studied used condoms prior to January 1986. RESULTS Antibodies to HIV developed in only one of the 14 wives. At the time when this seroconversion was detected, her husband, in whom AIDS developed, had been reactive for HIV antibody for 49 months, and showed positive findings for HIV antigen for 26 months. No additional risk factors were identified for this couple. The infected female spouse, however, has a 14-year history of multiple sclerosis, and had been treated with immunosuppressant intermittently. Despite a significantly reduced number of CD4 lymphocytes, she has remained clinically asymptomatic for 17 months since seroconversion. HIV antibodies did not develop in any of the 13 remaining wives, despite the frequent practice of oral sex by six couples and reports of occasional anal intercourse by another couple.(ABSTRACT TRUNCATED AT 400 WORDS)

C-terminal domain of the adenovirus E1A oncogene product is required for induction of cytotoxic T lymphocytes and tumor-specific transplantation immunity

Adenovirus genes required for the elicitation of adenovirus group C-specific cytolytic T lymphocytes (CTLs) and for the induction of adenovirus-specific transplantation antigen (TSTA) were identified by immunization with a library of adenovirus mutants. The group C Ad-specific CTL response was elicited by immunization with wild-type adenovirus type 5 (Ad5) or with recombinant adenoviruses containing Ad5 E1A gene. The specific CTL response was also elicited by Ad5 virus constructs which express only the 12 S or 13 S E1A early mRNA, but not with viruses unable to express E1A protein sequences normally encoded by the E1A early messages. The induction of transplantation immunity against tumorigenic Ad-transformed cells was studied next. The product encoded by either 13 S and 12 S E1A mRNA alone was sufficient for strong TSTA activity. A series of viruses with mutations within the first exon of the E1A message also induced strong TSTA, while Ad5 mutants with lesions within the second exon failed to induce syngraft immunity. These results provide strong evidence that amino acid sequence encoded by the second exon of the Ad5 E1A message is required, either directly or indirectly, for the induction of both Ad-specific CTL and Ad TSTA.

Tumorigenicity of adenovirus-transformed cells and their sensitivity to tumor necrosis factor α and NK/LAK cell cytolysis

Sensitivity of a library of cloned adenovirus-transformed rat cell lines of varying tumorigenicity to cytotoxic action of tumor necrosis factor alpha (TNF alpha) was studied and correlated with their sensitivity to NK/LAK cell cytolysis. Our data confirm earlier reports that expression of the E1A oncogene of Ad2 or Ad5 is associated with sensitivity of transformed cells to TNF alpha and also NK/LAK cytotoxicity. Ad2-transformed cell line which expresses the E3 early region in addition to the E1 gene block is resistant to TNF alpha, but remains sensitive to NK/LAK cells. All cell lines which express the E1A oncogene of highly oncogenic Ad12 are resistant to NK but not LAK cells. Their sensitivity to TNF alpha, however, varies over a broad range and does not correlate with either their susceptibility to NK/LAK cytolysis or their tumorigenic potential.

MIXED LYMPHOCYTE REACTION-INDUCED RELEASE OF SOLUBLE IL-2 RECEPTOR

We studied the release of soluble interleukin 2 receptor (sIL-2R) by PBMC in mixed lymphocyte reaction (MLR) in order to clarify the significance of high plasma levels of sIL-2R in transplant patients undergoing rejection. Levels of sIL-2R were shown to increase progressively after the first day of the MLR and reached their peak on day 5. This pattern of sIL-2R correlated with the incorporation of [3H]thymidine. CsA and prednisolone (PRED) were added at the beginning of the MLR and were shown to inhibit the release of sIL-2R. This inhibition correlated with an inhibition of the [3H]thymidine incorporation. When CsA and PRED were added 24 hr after the initiation of the MLR, a similar inhibition of sIL-2R release was observed, but when they were added 48 hr after the initiation or in the last day of the MLR little or no effect was observed. Incubation of responder or stimulator-responder cells with either CsA or PRED before the initiation of MLR showed that only CsA preincubation was accompanied by decreased [3H]thymidine incorporation. Preincubation with CsA inhibited the release of sIL-2R, whereas PRED had a variable effect. Recombinant IL-2 was shown to augment the release of sIL-2R even at very low doses, but it did not alter significantly MLR-induced [3H]thymidine incorporation. The addition of rIL-2 at the initiation of the MLR was also shown to reverse completely the PRED inhibition of the MLR-induced release of sIL-2R and of the [3H]thymidine incorporation. Addition of rIL-2 reversed only partially CsA-induced inhibition. Addition of different concentrations of sIL-2R at the initiation of the MLR were not shown to affect incorporation of [3H]thymidine. We conclude that the release of sIL-2R in response to alloantigens is an IL-2-dependent phenomenon, and determination of its levels might be a useful indicator of either in vitro or in vivo alloantigen responses and of the effectiveness of immunosuppressive treatment.