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M L Kripke

Publications and source records attributed to M L Kripke.

At least 19 recordsLinked to original sources
PubMed1992

Pyrimidine dimers in DNA initiate systemic immunosuppression in UV-irradiated mice.

Exposing the skin of mice to UV radiation interferes with the induction of delayed and contact hypersensitivity immune responses initiated at nonirradiated sites. The identity of the molecular target in the skin for these immunosuppressive effects of UV radiation remains controversial. To test the hypothesis that DNA is the target for UV-induced systemic immunosuppression, we exposed C3H mice to UV radiation and then used liposomes to deliver a dimer-specific excision repair enzyme into the epidermis in situ. The application of T4 endonuclease V encapsulated in liposomes to UV-irradiated mouse skin decreased the number of cyclobutane pyrimidine dimers in the epidermis and prevented suppression of both delayed and contact hypersensitivity responses. Moreover, the formation of suppressor lymphoid cells was inhibited. Control, heat-inactivated endonuclease encapsulated in liposomes had no effect. These studies demonstrate that DNA is the major target of UV radiation in the generation of systemic immunosuppression and suggest that the primary molecular event mediating these types of immunosuppression by UV radiation is the formation of pyrimidine dimers. Furthermore, they illustrate that the delivery of lesion-specific DNA repair enzymes to living skin after UV irradiation is an effective tool for restoring immune function and suggest that this approach may be broadly applicable to preventing other alterations caused by DNA damage.

Analysis of Variance↗
PubMed1992

N-ras mutation in ultraviolet radiation-induced murine skin cancers.

UV radiation is a potent DNA-damaging agent and a known inducer of skin cancer in experimental animals. To elucidate the role of oncogenes in UV carcinogenesis, we analyzed UV-induced murine skin tumors for mutations in codon 12, 13, or 61 of Ha-ras, Ki-ras, and N-ras oncogenes by amplification of genomic tumor DNAs by the polymerase chain reaction followed by dot-blot hybridization to synthetic oligonucleotide probes designed to detect single base-pair mutations. In addition to UV-induced C3H mouse skin tumors, we also analyzed skin tumors induced in the same strain of mice by other carcinogenic agents such as 8-methoxypsoralen + UVA, angelicin + UVA, dimethylbenz-[a]anthracene + UV + croton oil, and 4-nitroquinoline-1-oxide. We found that 4 of 20 UV-induced skin tumors contained either C----A or A----G base substitutions at N-ras codon 61. In addition, 2 of 5 melanomas possessed a G----A transition in N-ras codon 13 and an A----T transversion in N-ras codon 61, respectively. Interestingly, none of the 8-methoxypsoralen + UVA- or angelicin + UVA-induced tumors we analyzed contained mutations in any of the ras genes. However, 1 of 4 4-nitroquinoline-1-oxide-induced tumors exhibited a G----T transversion at Ki-ras codon 12, a potential site for formation of a 4-nitroquinoline-1-oxide adduct with a guanine residue. We also found that 2 nonmelanoma tumors induced by dimethylbenz[a]anthracene + UV + croton oil contained an A----T transversion at Ha-ras codon 61 position 2, which is characteristic of most dimethylbenz[a]anthracene-induced tumors. These results suggest that UV-induced C3H mouse tumors display mutations preferentially in the N-ras oncogene. Since most N-ras mutations in UV-induced tumors occurred opposite dipyrimidine sequences (T-T or C-C), one can infer that these sites are the targets for UV-induced mutation and transformation.

Animals↗
PubMed1992

Studies on the mechanism of immunologic tolerance induction by murine dendritic epidermal Thy-1+ cell lines.

We are investigating the functions of the Thy-1+ dendritic cells present in murine epidermis. Dendritic epidermal Thy-1+ cell (DETC) lines conjugated in vitro with hapten induce specific immunologic tolerance upon intravenous (i.v.) or subcutaneous injection into the footpad of normal mice. In these studies, we demonstrate that hapten-conjugated cells of other long-term, interleukin-2 (IL-2)-dependent, T cell lines are unable to induce tolerance upon footpad injection, indicating that the ability of DETC lines to induce tolerance is not a function of long-term cell culture or IL-2 dependence. Suppressor T cells were not found in mice made tolerant by footpad injection of hapten-conjugated cells of the DETC line AU16, although they could be demonstrated in mice made tolerant by i.v. injection. Studies of lymphocyte proliferation in vitro suggested that hapten-conjugated AU16 cells may induce tolerance by inhibiting the proliferation of activated T lymphocytes.

Animals↗
PubMed1992

Immunobiology of primary murine melanomas.

Primary cutaneous melanomas can be induced in inbred mice by applying a dose of dimethylbenz[a]anthracene to the skin of 4-day-old mice, and then applying repeated doses of a tumor promoter to the same site over a long period of time. Preliminary experiments suggest that the final incidence of melanomas is strongly influenced by the age at which the initiating dose of carcinogen is applied. Melanomas induced by this method in C3H mice are immunogenic and exhibit a high degree of cross-reactivity when tested by immunization and challenge in vivo. Exposing the mice to ultraviolet (UV) radiation during carcinogenesis dramatically accelerates the appearance of melanoma. We are attempting to determine how UV radiation potentiates melanoma induction by studying the growth of melanoma cells transplanted into UV-irradiated skin. Our studies suggest that UV irradiation accelerates the outgrowth of melanoma cells by means of a local, immunosuppressive effect on the skin. However, this effect is distinct from the ability of UV irradiation to alter epidermal Langerhans cells and interfere with the induction of contact hypersensitivity responses. We postulate that UV irradiation augments melanoma development by interfering with the efferent arm of the immune response in the UV-irradiated site.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Effect of local ultraviolet irradiation on infections of mice with Candida albicans, Mycobacterium bovis BCG, and Schistosoma mansoni.

In this study, we investigated whether mice given ultraviolet (UV)-B (280-320 nm) radiation in doses sufficient to alter cutaneous immune cells and impair the induction of contact hypersensitivity would also have impaired resistance to infectious agents administered at the site of UV irradiation. C3H mice were exposed to 400 J/m2 UVR from FS40 sunlamps on four consecutive days. Immediately after the last UV treatment, groups of mice were injected subcutaneously with Candida albicans, injected intradermally (ID) with Mycobacterium bovis bacillus Calmette-Guerin (BCG), or infected percutaneously with Schistosoma mansoni in UV-irradiated skin. The induction of the delayed hypersensitivity response to C. albicans and BCG, as assessed by footpad swelling, was unaffected by UV irradiation. However, the number of viable mycobacteria recovered from the lymphoid organs of BCG-infected mice was increased significantly in the UV-irradiated animals for a period of more than 2 months. Low-dose UV irradiation of the skin at the site of infection did not influence the number of S. mansoni parasites recoverable from the internal organs of mice that had been infected with cercariae percutaneously 6 weeks earlier. We conclude that the ability of UV radiation to impair the development of cell-mediated immunity to antigens introduced in a UV-irradiated site is not universal and depends on the particular antigen administered. We hypothesize that the involvement of epidermal Langerhans cells as the primary antigen-presenting cells in the induction of cell-mediated immunity may be the critical factor in determining whether a particular immune response will be affected by local UV irradiation.

Animals↗
PubMed1992

Internalization of Ia molecules into Birbeck granule-like structures in murine dendritic cells.

Dendritic cells isolated from the draining lymph nodes of mice sensitized epicutaneously with hapten are potent antigen-presenting cells and contain Birbeck granules and cored tubules characteristic of antigen-activated epidermal Langerhans cells. We used immunogold labeling and transmission electron microscopy to follow the internalization of Ia molecules in these antigen-presenting cells. We found that Ia molecules were internalized into Birbeck granule-like structures in the antigen-activated dendritic cells. Computer reconstruction of serial sections of the dendritic cells demonstrated that these structures span the cytoplasm from the cell membrane to the nuclear membrane and are associated with lysosomes. The internalization of Ia molecules into these structures supports the hypothesis that the Birbeck granule-like structures are derived from the cell membrane and are involved in the antigen-processing/presenting function of the dendritic cells.

Animals↗
PubMed1992

Characteristics of antigen-presenting cells involved in contact sensitization of normal and UV-irradiated mice.

Exposure of mice to ultraviolet (UV)-B (280-320 nm) radiation alters their immune response to contact-sensitizing haptens applied to UV-irradiated skin. Under these conditions, the contact-hypersensitivity response is reduced, and hapten-specific suppressor T lymphocytes can be found in the spleen. Considerable evidence suggests that the epidermal Langerhans cell is one of the principal targets of this effect of UV irradiation that leads, ultimately, to suppressor cell formation. We are using a combination of cell-surface markers and light and electron microscopy to determine whether differences can be detected in the antigen-presenting cells involved in contact sensitization of normal and UV-irradiated mice.

Animals↗
PubMed1992

Effects of ultraviolet radiation on the pathogenesis of Mycobacterium lepraemurium infection in mice.

The purpose of this study was to determine whether exposing mice to ultraviolet radiation (UVR) would alter the pathogenesis of infection with Mycobacterium lepraemurium (MLM), which causes a chronic, progressive, lethal disease in susceptible mouse strains. BALB/c mice were irradiated on dorsal skin with various doses of UVR from FS40 sunlamps 3 days before infection with MLM in the hind footpad. The course of disease was followed by assessing the number of acid-fast bacteria in the footpad, regional lymph node and spleen, and measuring the size of the lesion at the site of MLM infection at various times after infection. Mice were also tested periodically for a delayed-type hypersensitivity (DTH) response by injecting MLM antigen into the uninfected footpad and measuring footpad swelling 24 hours later. Mice treated with a single high dose of UVR (45 kJ/m2) had significantly more bacteria in the infected footpad, lymph node and spleen than unirradiated control animals. They also had larger lesions at the site of MLM infection and exhibited significant suppression of the DTH response at 3 and 6 months after infection. Injection of mice s.c. in the footpad with MLM 3d after 45 kJ/m2 UVR reduced the median survival time from 391 to 305 d and after i.v. infection from 171 to 139 d. Dose-response studies indicated that exposing mice to 2.3 kJ/m2 of UVR, which is approximately 1 minimal erythemal dose for this strain, suppressed the DTH response by 50% at 3 months after infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Lack of correlation between UV-induced enhancement of melanoma development and local suppression of contact hypersensitivity.

Injection of melanoma cells into the UV-irradiated ear skin of syngeneic mice results in an increased incidence of melanomas compared with that in nonirradiated ear skin. This effect of UV is localized to the site of irradiation and appears to be immunologically mediated. In these studies we test the hypothesis that the effect of UV irradiation on melanoma development is related to its ability to alter epidermal Langerhans cells and impair the induction of contact hypersensitivity. A regimen of UV irradiation that altered epidermal immune cells and interfered with the generation of contact hypersensitivity was tested for its ability to increase the incidence of melanoma. Conversely, the ear skin of C3H mice treated with a regimen of UV radiation that enhanced melanoma development was examined for the number of appearance of ATPase+ and Thy-1+ dendritic epidermal cells and tested for the ability to initiate a contact hypersensitivity response. No correlation between these effects of UV irradiation could be detected. Furthermore, implantation of melanoma cells into UV-irradiated ear skin resulted in the generation of systemic immunity against subsequent tumor challenge. Therefore, we conclude that the ability of UV irradiation to modify melanoma development is unrelated to its effects on the afferent arm of the contact hypersensitivity response and that enhanced melanoma development is not due to an impairment in the induction of tumor immunity.

Adenosine Triphosphatases↗
PubMed1992

Antigen presentation in the skin: modulation by u.v. radiation and chemical carcinogens.

The skin provides an excellent model to investigate antigen presenting cells (APC) particularly using contact hypersensitivity responses. The skin has its own distinct APC of which Langerhans cells (LC) are the best characterized. Fluorescein isothiocyanate (FITC) has proved a useful reagent with which to follow antigen-labeled APC to draining lymph nodes, where they bind to T lymphocytes. Cluster formation appears to be a necessary component of the APC-T cell interaction. Both u.v. radiation and chemical carcinogens are able to alter LC in the skin, resulting in immunological tolerance when antigen is presented through such treated sites. The changes in APC function are linked mainly to the tumor promoting action of carcinogens. The nature of the APC that trigger suppressor circuits and the potential chemical mediators involved are discussed. These studies have important implications for the immunobiology of the skin and for cutaneous carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

Effect of psoralen plus ultraviolet A radiation on in vivo growth of melanoma cells.

Exposure of murine skin to UVB (280-320 nm) radiation accelerates the outgrowth of melanoma cells implanted into the irradiated site. Because many of the biological effects of psoralen plus UVA (320-400 nm) radiation (PUVA) resemble those of UVB radiation and because PUVA therapy is used extensively in the treatment of cutaneous diseases in humans, we determined the effect of PUVA on the growth of transplanted murine melanoma cells. Unshaved C3H/HeN(MTV-) mice were treated twice each week for 3 weeks with 0.4 mg 8-methoxypsoralen i.p. plus 4.25 kJ/m2 UVA radiation; syngeneic K1735 melanoma cells were then injected s.c. into the external ear. This treatment stimulated the outgrowth of the melanomas compared to that in untreated mice and mice treated with 8-methoxypsoralen or UVA alone. The use of a nonphototoxic, monofunctional psoralen plus UVA was equally effective, indicating that neither phototoxicity nor the ability to form DNA crosslinks was required for this effect. In vitro treatment of a murine keratinocyte cell line PAM 212 with PUVA caused the release of soluble factors that, when mixed with K1735 melanoma cells prior to injection, stimulated their outgrowth in vivo. These studies demonstrate that PUVA treatment can contribute to the pathogenesis of melanoma by exerting a stimulatory effect on the outgrowth of melanoma cells. Furthermore, they suggest that this effect may result from the ability of PUVA to cause the release of stimulatory factors from keratinocytes.

Animals↗
PubMed1991

Evidence that the local effect of ultraviolet radiation on the growth of murine melanomas is immunologically mediated.

We had reported previously that the outgrowth of melanoma is enhanced when melanoma cells are injected into UV-irradiated skin of syngeneic mice. To determine whether this effect was specific for melanomas, we compared the growth of 13 different tumor cell lines (3 melanomas, 6 fibrosarcomas, 2 undifferentiated skin tumors, a squamous cell carcinoma, and a spontaneous hepatocarcinoma) in UV-irradiated and nonirradiated syngeneic mice. C3H/HeN(MTV-) mice were exposed to 4.8 kJ/m2 UV-B (280-320 nm) radiation twice a week for 3 weeks; the tumor cells were injected into the UV-irradiated pinna 24 h after the final UV irradiation. The growth of all the melanomas and 4 of the fibrosarcomas was enhanced in UV-irradiated mice, indicating that the effect of UV radiation was not specific for melanomas or tumors of a particular etiology. Using an in vivo immunization and challenge assay, we found that the 7 tumors exhibiting enhanced development in UV-irradiated skin were highly immunogenic, whereas the remaining 6 tumors were not. This suggested that enhanced tumor outgrowth resulted from an immunosuppressive effect of the UV radiation. When tested further, we found that UV-B radiation had no effect on melanoma outgrowth in congenitally athymic mice, sublethally X-irradiated mice, or mice depleted of Thy1+ cells in vivo. These results indicate that immunological mechanisms play a role in the effect of UV radiation on the growth of murine melanomas.

Animals↗
PubMed1991

Antigen-presenting activity of draining lymph node cells from mice painted with a contact allergen during ultraviolet carcinogenesis.

The induction of skin cancers in mice by chronic UV irradiation is accompanied by a decrease in the numbers of Ia+ and Thy-1+ dendritic cells in the epidermis early in the course of UV irradiation. Subsequently, the number of Ia+ cells, but not Thy-1+ cells, increases until the time of tumor development. To assess the functional significance of these changes in cutaneous immune cells, and to help define the role these cells may play in immune surveillance against skin cancers, we tested the afferent immunologic capability of the skin during the development of UV-B radiation-induced skin cancers. Afferent immune function was measured by testing the Ag-presenting capacity of draining lymph node (DLN) cells from mice sensitized epicutaneously with dinitrofluorobenzene. A reduced contact hypersensitivity response was induced in mice immunized with DLN cells from UV-irradiated mice that had been sensitized with hapten on UV-irradiated skin. This decreased reactivity was present during the entire latent period of tumor development. However, in tumor-bearing mice, the DLN cells from UV-irradiated, sensitized animals exhibited normal Ag-presenting activity. DLN cells from UV-irradiated mice sensitized on ventral, unirradiated skin exhibited normal Ag-presenting activity. The lowest amount of Ag-presenting activity in the draining lymph nodes of UV-irradiated mice correlated temporally with the lowest number of Ia+, adenosine triphosphatase+ dendritic epidermal cells in the UV-irradiated skin. At least during the early part of the tumor latent period, an increase in the number of these cells was paralleled by an increase in the Ag-presenting activity of the DLN cells. In contrast, the number of Thy-1+ dendritic epidermal cells in UV-irradiated skin did not correlate with the Ag-presenting activity. Thus, the decrease in the number of identifiable epidermal Langerhans cells early in the course of chronic UV irradiation correlated with a decrease in Ag-presenting activity after sensitization through the UV-irradiated skin. These studies demonstrate that the afferent arm of the cutaneous immune response is impaired in the site of tumor development throughout the latent period of UV carcinogenesis.

Animals↗
PubMed1991

Photoimmunology of experimental melanoma.

Increases in the incidence of cutaneous melanoma during the past few decades has drawn attention to the possible causes of this cancer. Although sunlight exposure has long been suspected of being a contributing factor, direct evidence of its participation has been difficult to obtain using epidemiological approaches. We have used murine models to investigate the possible contributions of UV radiation to the induction and pathogenesis of melanoma. Our studies demonstrate that UV radiation contributes to the induction of melanoma in a variety of ways, including an indirect, local effect on the skin. Recent evidence suggests that this indirect effect is immunologically mediated.

Animals↗
PubMed1991

Local suppression of contact hypersensitivity in mice by a new bifunctional psoralen, 4,4',5'-trimethylazapsoralen, and UVA radiation.

Although psoralens plus UVA radiation (320-400 nm) have been widely used for the treatment of dermatologic diseases, the toxic effects of these agents have led investigators to develop new photochemotherapeutic compounds. One such compound is 4,4',5'-trimethylazapsoralen (TMAP), a new bifunctional molecule. The purpose of this study was to examine the immunologic side effects of repeated treatment of C3H mice with TMAP plus UVA radiation. During this treatment, the number of ATPase+, la+, and Thy-1+ dendritic epidermal cells greatly decreased in the treated site, despite the lack of phototoxicity. The reduction in the number of detectable cutaneous immune cells was accompanied by a decrease in the induction of contact hypersensitivity to dinitrofluorobenzene applied to the treated skin, an impairment in the antigen-presenting activity of draining lymph node cells, and the presence of suppressor lymphoid cells in the spleen of unresponsive mice. Treatment with UVA radiation alone also reduced the number of ATPase+, Ia+, and Thy-1+ cells in the skin, but did not cause any detectable alterations in immune function. This implies that morphologic alterations in these cells do not necessarily indicate loss of function. Thus, although TMAP in combination with UVA radiation is not overtly phototoxic, it is highly immunosuppressive in mice.

Animals↗
PubMed1991

Activation of keratinocytes with psoralen plus UVA radiation induces the release of soluble factors that suppress delayed and contact hypersensitivity.

Exposure of mice to psoralen plus ultraviolet A (320-400 nm) radiation or midrange ultraviolet B (280-320 nm) radiation causes a systemic suppression of the immune response. Although the mechanisms involved in the induction of suppression are not entirely clear, recent studies have demonstrated that ultraviolet B--irradiated keratinocytes release soluble factors that depress delayed-type hypersensitivity to alloantigens and activate the suppressor cell pathway. The purpose of this study was to determine whether PUVA-treated keratinocytes could also cause the release of such immunosuppressive factors. Treatment of keratinocytes with psoralen and UVA radiation induced the release of a factor that depressed the delayed-type hypersensitivity reaction to alloantigen. The suppressive factor was released regardless of whether the psoralen formed monofunctional or bifunctional adducts with DNA and regardless of its phototoxicity. In addition, keratinocytes treated with psoralen and lower doses of UVA radiation released a factor that inhibited contact but not delayed-type hypersensitivity, suggesting that more than one immunosuppressive factor is released following treatment of keratinocytes with appropriate doses of psoralen and UVA radiation. Our findings provide evidence that immunosuppressive factors released from keratinocytes may play a role in the induction of systemic immune suppression following PUVA treatment. Moreover, they demonstrate that PUVA treatment, unlike UVB treatment, can cause the release of more than one immunosuppressive factor from keratinocytes.

Animals↗
PubMed1991

Supernatants from ultraviolet-irradiated keratinocytes decrease the resistance and delayed-type hypersensitivity response to Mycobacterium bovis bacillus Calmette-Guerin in mice and impair the phagocytic ability of macrophages.

We recently demonstrated that exposure of mice to a single high dose or multiple smaller doses of ultraviolet (UV) radiation decreased the induction of the delayed-type hypersensitivity (DTH) response to bacillus Calmette-Guerin (BCG) from Mycobacterium bovis injected into unexposed sites. In view of the limited ability of UV radiation to penetrate beyond the epidermis and upper layers of the dermis, it is not entirely clear how exposing the dorsal skin of mice to UV radiation causes systemic impairment of the immune response to BCG. In this study we report that mice injected with supernatants from keratinocyte cultures exposed to UV radiation in vitro impaired host resistance to BCG. Both induction and elicitation of the DTH reaction were suppressed after the intravenous injection of supernatants from UV-irradiated keratinocytes. Furthermore, these supernatants interfered with the elimination of viable bacteria from the lymphoid organs. To determine whether macrophages were the target of the UV-induced, keratinocyte-derived, suppressive cytokine, macrophages were isolated from mice injected with the suppressive cytokine or treated in vitro with the supernatants and tested for their ability to ingest and kill BCG in vitro. Injection of the suppressive factor significantly reduced the phagocytosis of BCG by the macrophages but did not alter the rate of intracellular killing. Similarly, phagocytosis was reduced when normal macrophages were treated in vitro with the suppressive factor. These findings suggest that the suppressive cytokine interferes with the elimination of bacteria in vivo by inhibiting the initial step in bacterial clearance, the uptake of the bacteria by host macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗