Clonal origin of tumors induced by ultraviolet radiation.

Skin tumors were induced in (C3H/HeN X C3H/HeN-PGK-1a)F1 female mice, heterozygous at the X-linked phosphoglycerate kinase-1 (PGK-1) locus, by exposure to the carcinogenic influence of ultraviolet radiation (UVR), 3-methylcholanthrene [(MCA) CAS: 56-49-5], or benz[a]pyrene [(BP) CAS: 50-32-8]. An assessment of the clonal origin of these tumors was accomplished through an analysis of the PGK-1 enzyme phenotype expressed by the transformed cells. In vitro culture was employed as a means of depleting nontransformed cells of host origin from the induced tumors. Cultured lines derived from tumors induced by each of the above agents were found to express only one of the two enzyme forms encoded by the host genotype, consistent with the probability that all the UVR-, MCA-, and BP-induced tumors examined in this study were monoclonal in origin. For further substantiation of the monoclonality of UVR-induced tumors, 2 UVR-induced tumors were enzymatically dissociated immediately following excision from the primary hosts, and the resulting cell suspensions were cloned in soft agar. Upon analysis, each set of clones selected in soft agar expressed only a single PGK-1 enzyme form. To rule out the possibility that the apparent monoclonality of culture-adapted tumor lines was due to in vitro selection, tumors that arose in UVR-treated PGK-1a/b female heterozygote mice were transplanted into PGK-1a and PGK-1b homozygous recipients. These transplanted tumors expressed a single PGK-1 allozyme following growth in recipients that were genetically homozygous for the major PGK-1 enzyme form expressed by the tumor prior to transplantation. These data strongly support the concept that most, if not all, UVR-induced tumors are derived from the progeny of a single transformed cell. This observation is important to the understanding of the nature of tumor-specific transplantation antigens expressed by individual UVR-induced tumors and indicates that such antigens also are clone specific. In addition, the results of this study indicate that polyclonality does not play a significant role in the generation of cellular and phenotypic heterogeneity known to be present within individual UVR-induced tumors.

Ability of cyclosporine to promote the growth of transplanted ultraviolet radiation-induced tumors in mice.

The use of immunosuppressive agents (primarily azathioprine and prednisone) to promote human allograft survival is known to be associated with an enhanced rate of skin cancer development by ultraviolet radiation (UVR). These observations raise the question of whether the immunosuppressive agents are functioning as cocarcinogen or whether they augment UVR-induced tumors by their successive influence on normal tumor-directed immune responses. In this report we have examined the effect of cyclosporine (CsA) on the capacity of murine UVR-induced tumors to grow following their transplantation to syngeneic recipients. We found that transplanted UVR tumors, selected for their inability to grow in normal recipients, were capable of progressive growth following implantation into CsA-treated recipients. This CsA-induced tumor-susceptible state could be reversed by treatment of prospective recipients with the drug cyclophosphamide (CY), supporting the concept that CsA was functioning in vivo by its capacity to promote suppressor cell generation. Further studies established that CsA treatment needed to be given at or near the time of tumor transplantation for susceptibility to occur. Our findings support the possibility that CsA is capable of promoting the survival and progression of UVR-induced skin tumors via its capacity to enhance the dominance of suppressor-cell-controlled immune responses.

Relationship between inducible H-2 expression and the immunogenicity of murine skin neoplasms. I. Evidence that the immunogenicity of ultraviolet radiation-chemically induced tumors is associated with their susceptibility to gamma-interferon-mediated enhancement of H-2Kk expression.

Our objective was to determine the relationship between major histocompatibility complex class I molecule expression and the tumorigenic properties of cutaneous neoplasms induced by ultraviolet radiation or chemical carcinogens. All tumors tested were found to express low constitutive levels of MHC class I molecules in vitro as determined by indirect immunofluorescence and flow cytometry. Those tumors capable of growth in UVR-exposed but not in normal recipients (regressors) were found to express enhanced levels of H-2Kk following incubation in the presence of gamma-IFN. In contrast, only one of the tumors that were capable of growth in normal recipients (progressors) exhibited more than moderate enhancement of H-2Kk expression in response to gamma-IFN. Analysis of tumor variants obtained by conversion of a UVR-induced regressor tumor to the progressor phenotype by passage through sublethally gamma-irradiated hosts, or the generation of regressor tumors by mutagen exposure of a benz [A] pyrene (BAP) induced progressor tumor, further supported the direct relationship between tumor immunogenicity in vivo and the capacity to elevate H-2Kk expression in response to gamma-IFN. No correlation existed between H-2Dk expression by the tumors and their transplantation phenotype. Furthermore, we failed to observe MHC class II expression by any of the tumors tested. Finally, the growth rate of a regressor tumor implanted into UVR-exposed hosts was significantly reduced if the tumor was pretreated with gamma-IFN in vitro prior to inoculation. This result suggests that UVR-exposed animals may be deficient in their ability to enhance the expression of MHC class I molecules on developing tumors. This alteration may, in part, account for the state of tumor susceptibility caused by UVR exposure.

Mood, memory, and social judgments in children.

The influence of positive and negative moods on children's recall and recognition memory and impression-formation judgments was investigated in a two-list experimental design. A total of 161 schoolchildren, 8 to 10 years old, were presented with audiovisual information containing positive and negative details about 2 target children. Each presentation was preceded by happy or sad mood manipulations. One day later, the children were again placed in a happy or sad mood, and their recall and recognition memory and impression-formation judgments were assessed. Results showed that memory was better when (a) the children felt happy during encoding, retrieval, or both; (b) the material was incongruent with learning mood; (c) the 2 target characters were encountered in contrasting rather than in matching mood states; and (d) recall mood matched encoding mood. A happy mood increased the extremity of both positive and negative impression-formation judgments. Results are contrasted with experimental data obtained with normal or depressed adults, and implications are considered for contemporary theories of mood effects on cognition and for social-developmental research.

Effects of real gender and labeled gender on adults' perceptions of infants.

Three experiments were conducted to discover factors mediating adults' perceptions of male and female infants. In the first experiment, college students were shown 30-s videotapes of four male and four female babies, each of whom was randomly labeled with a male or a female name. Infants labeled as male were perceived as significantly more masculine and stronger than those labeled as female. Discriminant analyses revealed that both rated masculinity and the combination of ratings on male stereotyped traits differentiated infants labeled as male or female. Analyses of real gender revealed that boys were rated as less sensitive and stronger than girls. Discriminant analyses suggested that the combination of less sensitive, more of a problem, more mature, and more playful best differentiated real males from real females. In Experiment 2, the findings of Experiment 1 were confirmed with a sample of mothers of young infants. In Experiment 3 college students' judgments of the sex of the eight babies were correctly predicted from the sensitivity ratings of these babies in Experiment 1. It appears that there is a complex of cues from which adults make judgments of infants' gender and inferences about their characteristics: Boys may appear stronger, more playful, and more of a problem, and girls seem to look more sensitive. Implications for further studies of gender labeling and for sex typing are discussed.

Apparent relative size in the judgment of apparent distance.

In experiment 1 judgments of the apparent distance of comparison figures (squares or triangles) were obtained under reduction conditions. These comparison figures were either shaped the same as or different from equidistant standard figures, and were half, equal to, or double the area of the standard figures. Apparent distance was found to be a linear function of the relative area of the comparison figure both in same-shape and different-shape stimulus pair conditions. In addition, apparent distance was found to be a function of perceived area, because in different-shape conditions triangles were generally seen to be closer than squares even when the real area of the standard and comparison was equal. The results of experiment 2 and 3 provide some evidence that the effect of different shapes of standard and comparison on apparent distance is due to the observers' perception of the height rather than the area of figures. The series of experiments shows that the traditional transactionalists' explanation of relative size as a cue for distance is inadequate.

Development of categorical identification of native and non-native bilabial stops: infants, children and adults.

Using an infant speech identification (ISI) procedure, English language environment infants, two- and six-year-old children, and adults were tested for their identification of sounds on a native (voiced/voiceless bilabial stop) and a non-native (prevoiced/voiced bilabial stop) speech continuum. Categorical perception of the two contrasts diverged as a function of age, increasing for the native contrast and decreasing for the non-native between two and six years. In Experiment 2, subjects of the same four ages were tested for their identification of a continuum of harmonic tones varying in pitch. Comparison of the results of Experiment 1 with the essentially continuous perception of this pitch continuum supports the view that the perception of the native contrast becomes more categorical with age, while perception of the non-native contrast becomes less categorical, especially at six years. Experiment 3, in which adults were tested on the three continua with a multi-trial open set procedure, demonstrated that results with the ISI procedure in Experiments 1 and 2 are comparable to results with more traditional methods. The results of the three experiments are discussed in terms of the role of specific linguistic experience in the development of categorical speech perception.

Involvement of prostaglandins in the immune alterations caused by the exposure of mice to ultraviolet radiation.

Our study was designed to analyze the possible involvement of prostaglandins in the mechanisms responsible for the depressions in contact hypersensitivity (CH) responsiveness observed in UVR-exposed animals. Low-dose UVR-exposed animals were found to exhibit a depressed capacity to elicit CH responses after hapten application to irradiated (devoid of Langerhans cells) or UVR-protected (normal Langerhans cells) dorsal skin surfaces. Normal responsiveness was observed in low-dose UVR-exposed animals sensitized through unirradiated ventral skin surfaces. Indomethacin treatment of low-dose UVR-exposed animals (to inhibit prostaglandin synthesis in vivo) caused a retention in the capacity to respond normally to CH induction to haptens applied to the nonirradiated, but not to irradiated, dorsal skin surfaces. High-dose UVR-exposed animals, which normally exhibit a depression in responsiveness to hapten sensitization, retained a normal capacity to elicit CH responses if treated with the drug indomethacin. These findings implicate prostaglandins in the pathogenesis of the immunologic hyporesponsiveness, observed in low- and high-dose UVR-exposed animals. Our studies also determined that under all experimental conditions where animals were contact sensitized through nonirradiated skin sites, CH-effector cells could be found in the draining lymph nodes. No CH-effector cells were observed in the lymph nodes of mice that were contact sensitized directly through irradiated skin sites. It was also found that the spleens of both UVR-exposed and normal animals contained adoptively transferrable suppressor cells subsequent to hapten application. This demonstration of CH-effector and CH-suppressor cells in both normal and UVR-exposed animals did not directly relate to the potential of the donor animals to elicit a CH response.

Implantation of thymic epithelial grafts into the anterior chamber of the murine eye: an experimental model for analyzing T-cell ontogeny.

The object of this investigation was to establish whether the intracameral implantation of thymic epithelial grafts could be utilized as a valid in vivo experimental model for probing the possible mechanisms whereby the sympathetic innervation of the thymus influences thymocyte dynamics. Our findings suggest that deoxyguanosine-treated thymic epithelial grafts, implanted into the anterior chamber of the eye, were receptive to host lymphoid progenitor cells, capable of supporting T-lymphocyte maturational processes, and were able to export mature T cells to the secondary lymphoid organs of a previously T-cell deficient host. In addition, we verified that the number of lymphoid cells recovered from a thymic epithelial graft which had been implanted into an anterior chamber devoid of sympathetic nerve input was generally greater than the number of lymphoid cells recovered from a matched graft which had been implanted into an anterior chamber which had an intact sympathetic nerve supply. Based on the results of these studies, investigative efforts can now be directed at studying a number of important aspects associated with the relationship between T lymphocyte ontogeny and the sympathetic nervous system.

Alpha-melanocyte-stimulating hormone exhibits target cell selectivity in its capacity to affect interleukin 1-inducible responses in vivo and in vitro.

The ability of i.v.-administered recombinant human interleukin 1 (IL 1 beta) to increase core body temperature, stimulate an increased production of serum amyloid P substance, and augment blood levels of circulating neutrophils in mice was inhibited in a dosage-dependent manner by administration of the neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH). alpha-MSH administration was also capable of inhibiting the capacity of i.v.-administered IL 1 beta to enhance plasma levels of corticosterone and to depress the generation and/or elicitation of contact hypersensitivity responses to skin-reactive chemicals. An analog of alpha-MSH (Nle4, D-Phe7 alpha-MSH), known to be more potent than native alpha-MSH in a number of melanotropin-sensitive systems, was determined to be more active than alpha-MSH in the modification of these same in vivo responses. Neither alpha-MSH nor its analog were capable of altering the capacity of IL 1 to stimulate increased plasma levels in prostaglandin E2 (PGE2). In vitro, neither alpha-MSH nor its analog were capable of reducing the capacity of IL 1 to stimulate fibroblast production of PGE2 or to augment the proliferation of murine thymocytes exposed to phytohemagglutinin. The apparent selectivity associated with the regulatory influences of alpha-MSH on IL 1-induced responses in vivo suggests that this neuropeptide may function as an endogenous inhibitor of certain immunomodulatory and inflammatory activities of the cytokine IL 1.

The role of macrophages in the regulation of high endothelial venule expression within the peripheral lymph nodes of mice exposed to ultraviolet radiation.

A number of direct and indirect immunologic consequences follow the exposure of the skin to ultraviolet radiation (UVR). One of the remote effects of UVR is the increased accumulation of lymphocytes within peripheral lymph nodes that drain irradiated skin sites. The present study was designed to evaluate the mechanisms responsible for this increased lymphocyte accumulation. Primary lymphocyte localization into draining regional lymph nodes was found to be markedly increased (up to 81%) by UVR exposure of the skin. The changes in lymphocyte localization correlated closely with increases in the number and density of lymphocyte-receptive endothelial structures (high endothelial venules, or HEV) within these regional lymph nodes. Because macrophages or their products are believed to maintain resting HEV expression and function, we assessed the role of these cells in the expansion of HEV due to UVR exposure. Our studies demonstrated that a peripheral injection of antigen-activated macrophages caused an increase in HEV expression within lymph nodes draining the injection site. Conversely, treatment of mice with silica or carrageenan to depress macrophage function produced both histologic and functional hyporesponsiveness of the microvascular endothelium to UVR-stimulated HEV expansion. These changes in endothelial cell responsiveness correlated with the absolute number of MAC-1+ cells present within the regional nodes of UVR-exposed mice. Our studies have demonstrated a striking similarity between lymph node microvascular changes in response to cutaneous UVR- and antigen-exposure. We therefore suggest that macrophage-mediated signals may initiate a general mechanism that increases lymphocyte recirculation through the regional lymph nodes in response to both antigenic and inflammatory challenge.