The dermis as a portal for dendritic cell-targeted immunotherapy of cutaneous melanoma

Complete surgical excision at an early stage remains the only curative treatment for cutaneous melanoma with few available adjuvant therapy options. Nevertheless, melanoma is a relatively immunogenic tumor type and particularly amenable to immunotherapeutic approaches. A dense network of cutaneous dendritic cells (DC) may account for the reported efficacy of vaccination through the skin and provide an attractive target for the immunotherapy of melanoma. Several phenotypically distinct DC subsets are discernable in the skin, among others, epidermal Langerhans cells and dermal DC. Upon appropriate activation both subsets can efficiently migrate to melanoma-draining lymph nodes (LN) to prime T cell-mediated responses. Unfortunately, from an early stage, melanoma development is characterized by strong immune suppression, facilitating unchecked tumor growth and spread. Particularly the primary tumor site and the first-line tumor-draining LN, the so-called sentinel LN, bear the brunt of this melanoma-induced immune suppression-and these are exactly the sites where anti-melanoma effector T cell responses should be primed by DC in order to prevent early metastasis. Through local immunopotentiation or through DC-targeted vaccination, the dermis may be utilized as a portal to activate DC and kick-start or boost effective T cell-mediated anti-melanoma immunity, even in the face of this immune suppression.

Severe feed restriction enhances innate immunity but suppresses cellular immunity in chicken lines divergently selected for antibody responses

The main aim of this study was to investigate the effects of different levels of feed restriction (FR) on immune responses of chicken lines divergently selected for high (H) and low (L) antibody responses to SRBC. We hypothesized that severe feed restriction suppresses immune responses and the level of immune suppression differs between birds with different genetic background. Therefore, we tested antibody responses, blood lymphocyte proliferative responses, and production of reactive oxygen intermediates (ROI) by Zymosan A-stimulated blood cells in chicken lines maintained on 3 levels of FR. The H line birds had significantly higher antibody responses, higher ROI production, and lower corticosterone (CORT) levels when compared with the L line birds. Feed restriction induced no significant effect on specific antibody responses to either a T helper 1- (Mycobacterium butyricum) or a T helper 2- (keyhole limpet hemocyanin) type antigen. Feed-restricted birds showed a marked reduction in natural antibodies binding lipoteichoic acid, in vitro lymphocyte proliferation in response to stimulation with concanavalin A, BW gain, and relative lymphoid organ weights compared with the birds fed ad libitum. However, FR birds showed a markedly enhanced ROI production, and plasma CORT levels compared with the birds fed ad libitum. The enhanced ROI production and suppressed lymphocyte proliferation coinciding with enhanced plasma CORT levels suggest stress-mediated immunomodulating effects of FR. A significant treatment by line interaction was found for ROI production; the increase of ROI production was larger in the H line than in the L line under severe FR. The increase in CORT levels was larger in the L line than in the H line under severe FR. Furthermore, the L line gained more BW than the H line under ad libitum conditions. Finally, under severe FR, relative spleen weight was lower in the L line than in the H line. The present findings suggest genetic differences affecting physiological and immunological responses under FR conditions.

Effect of Duration of Cold Stress on Plasma Adrenal and Thyroid Hormone Levels and Immune Responses in Chicken Lines Divergently Selected for Antibody Responses

There is increasing evidence that stress affects various immune processes. Some of these changes are due to hormonal changes involving corticosterone (CORT), triiodothyronine (T3), and thyroxine (T4). Effects of stress depend on the nature of specific stressors (e.g., thermal extremes, diet, pollutants), and stress-modifiers (e.g., genetic make-up, duration and severity of the stressors). We studied the effects of a specific stress (cold stress) with stress-modifiers (duration of stress and genotype of the bird) on immune responses and plasma adrenal and thyroid hormone levels in 3 layer-type chicken lines. Two lines were divergently selected for high (H line) or low (L line) antibody responses to SRBC, and the third line was a randombred control (C) line. Growing chicks (3- to 4-wk-old) of the 3 lines were feed-restricted at 80% of ad libitum consumption, and subjected to cold stress (CS) at 10 degrees C continuously for 7, 5, 3, 1, or 0 d before immunization with keyhole limpet hemocyanin (KLH). Specific antibody titers to KLH, and in vitro lymphocyte proliferation (LP) upon mitogen stimulation were measured. In addition, adrenal and thyroid hormone levels were measured in the plasma samples collected at the end of CS. No significant effect of duration of CS on specific antibody titers was found in the 3 lines. A significant enhancing effect of CS was found on LP. A significant dose-dependent suppressive effect of CS was found on plasma CORT levels. One day of CS had a significant enhancing effect on T3 levels. There was no significant effect of duration of CS on T4 levels. We conclude that CS does not affect specific antibody responses, but may have a modulating effect on cellular immunity and plasma CORT levels, depending on the duration of the stress. The present study suggests an inverse relationship between LP and CORT. This is the first study that reveals an absence of significant differences in adrenal and thyroid hormone levels in the described selection lines.

Differential Effects of Lipopolysaccharide and Lipoteichoic Acid on the Primary Antibody Response to Keyhole Limpet Hemocyanin of Chickens Selected for High or Low Antibody Responses to Sheep Red Blood Cells

Various bacterial components are potent activators of the innate immune system and probably (in)directly determine subsequent specific immune responses. Therefore, effects of i.v. administered Salmonella enteriditis-derived lipopolysaccharide (LPS) and Staphylococcus aureus-derived lipoteichoic acid (LTA), respectively, on the primary antibody (Ab) response to keyhole limpet hemocyanin (KLH) were studied in cocks from 2 lines divergently selected for high (H line) and low (L line) Ab responses to SRBC. The Ab responses to KLH were significantly affected by a line-by-treatment-by-time interaction. Significantly higher Ab titers to KLH, S. aureus LTA, and S. enteriditis LPS were found in H line birds than in the L line birds. Ab titers to KLH were enhanced if the chickens were intravenously pretreated 24 h earlier with LTA but decreased if the chickens were intravenously pretreated 24 h earlier with LPS. Ab responses to S. enteriditis LPS were significantly enhanced when birds were immunized with KLH or pretreated with S. aureus LTA. Ab responses to S. aureus LTA were also significantly enhanced when birds were immunized with KLH or pretreated with LTA and subsequently immunized with KLH. Our findings suggest that LTA and LPS have immunomodulatory features in chickens, albeit in opposite directions. In addition, KLH acted in an immunomodulatory role too. Possible mechanisms underlying our observations and the role of LTA and LPS in polarization of the specific immune response in chickens are discussed.

Durations of cold stress modulates overall immunity of chicken lines divergently selected for antibody responses

Effects of different durations of cold stress (CS) and the time point of immunization relative to the CS of 3 chicken lines were studied. The first 2 chicken lines were divergently selected for high and low antibody responses, and the third was a random-bred control line. In 2 experiments, 26-d-old growing chicks of the 3 lines were feed restricted at 80% of ad libitum and subjected to CS of 10 degrees C for 7, 2, or 0 d. Birds were immunized with keyhole limpet hemocyanin (KLH) at -1, +1, +3, +5, or +7 d relative to the end of the CS treatment. Specific antibodies to KLH were determined. In addition, in vitro lymphocyte proliferation responses to concanavalin A (ConA) and KLH as measures of cell-mediated immunity, production of zymosan-induced reactive oxygen intermediates as a measure of phagocytosis, and BW gain as a measure of a production trait were determined. Significantly higher antibody responses to KLH were found in the high line as compared with the other 2 lines. Specific antibody responses to KLH were not significantly affected by the CS treatments. CS had a delayed effect on in vitro mitogen responses to ConA. In vitro lymphocyte proliferation responses to ConA were higher in the low line birds than in the other 2 lines. In general, 7 d of CS significantly enhanced cellular immunity to ConA in vitro, whereas the 2-d CS treatment had differential effects on lymphocyte proliferation to ConA, depending on the line of bird and the time of immunization. KLH-specific lymphocyte proliferation was enhanced by 2 d of CS at 28 d after immunization. Effects of various CS treatments and the time of immunization on the production of reactive oxygen intermediates were inconsistent. In addition, BW gain was negatively affected by CS. We concluded that the innate part of the immune system (phagocytes) responded immediately to CS with an as yet unexplained variability, irrespective of the genetic background. When CS was prolonged, the cellular adaptive immune response and, to some extent, the specific humoral immune response were also affected. The lack of line-by-treatment interactions suggested that the genetic background was a prominent factor for the magnitude of the specific immune response. Our data confirmed earlier studies that, under restricted feeding with simultaneous stress (energy demand for thermoregulation and growth), cellular immunity is more sensitive than humoral immunity. A negative correlation between BW gain and cellular immunity suggest a trade-off between these 2 life traits.

Effects of cold stress on immune responses and body weight of chicken lines divergently selected for antibody responses to sheep red blood cells

Effects of cold stress (CS) on the immune system of chicken lines divergently selected for high (H line) and low (L line) antibody responses to SRBC next to a randombred control (C) line were studied. Three- to four-week-old growing chicks of the three lines were feed-restricted at 80% ad libitum and subjected to CS at 10 degrees C continuously for 7, 5, 3, 1, or 0 d prior to immunization with keyhole limpet hemocyanin (KLH). Specific and natural antibodies were measured in the three chicken lines subjected to or not subjected to various durations of CS prior to immunization. In addition to antibodies we also measured in vitro lymphocyte proliferation as a measure of cell-mediated immunity (CMI), zymosan-induced reactive oxygen intermediates (ROI) production as a measure of phagocytosis, and BW gain as a measure of production trait. In general, significantly higher antibody responses to KLH and natural antigens were found in the H line as compared to the other two lines. Specific antibody responses to KLH were not significantly affected by CS, but an acute transient increase in natural antibody titers to ovalbumin was found in H line birds subjected to 1 d of CS, which was not found in C or L line birds. On the other hand, an acute significant increase in natural antibody titers to lipopolysaccharide (LPS) was found in C and L line birds subjected to 1 d CS but not in H line birds. Cold stress enhanced the ROI production. In addition, 7 d of CS significantly enhanced cellular immunity in vitro, but no significant line effects with respect to cellular immunity were found. BW gain was negatively affected by CS, especially when CS was applied for longer periods. We concluded that birds responded immediately to CS with enhanced innate (phagocyte and natural antibody) immunity, irrespective of genetic background. When CS is prolonged, the cellular adaptive immune response is affected also. Although reallocation of energy was not measured, our data suggested that under limited conditions (e.g., restricted feeding) with simultaneous stress (e.g., CS), growth and cellular immunity were more sensitive than thermoregulation and humoral immunity. With respect to vital life traits, thermoregulation may have first priority followed by adaptive cellular immunity, humoral immunity, and BW gain. The relationships between immune responses and adaptation to stress are discussed.