[Acute lymphoblastic leukemia in childhood treated with non-T-cell depleted bone marrow transplantation from an HLA 2 loci (HLA-A and-DRB1)-mismatched mother after early graft failure of cord blood transplantation].

An 11-year-old boy with acute lymphoblastic leukemia received unrelated cord blood transplantation at the second remission. Because of early graft failure, he was given a second non-T-cell depleted bone marrow transplant from his HLA 2 loci (HLA-A and -DRB1)-mismatched mother 36 days after the first transplantation. Feto-maternal microchimerism was verified before transplantation. The second transplantation was performed with fludarabine/melphalan as a conditioning regimen, and tacrolimus/short-course methotrexate as graft-versus-host disease (GVHD) prophylaxis. Engraftment was prompt with a recovery of neutrophils (> 0.5 x 10(9)/1) by day +10, reticulocytes (> 1%) by day +17 and platelets (> 50 x 10(9)/l) by day +18. Mild regimen-related toxicities (grade I gastrointestinal, grade II hepatic) were observed and acute GVHD was grade I (skin: stage 2). No severe complication was noted. At 6 months post-transplantation, he had no chronic GVHD or leukemia relapse. This experience indicates the future feasibility of a back-up non-T-cell depleted transplantation from HLA 2 loci-mismatched and feto-maternal microchimerism-positive mothers in cases with primary graft failure.

Differential effect of phototherapy on the activities of human natural killer cells and cytotoxic T cells.

Exposure to ultraviolet B (UV-B) light is recognized to induce suppression of certain immune responses, particularly delayed hypersensitivity. However, its effect on cytotoxic T lymphocyte (CTL) activity, of major importance in the resistance to viruses and tumours, has not been assessed to the same extent. In this study five normal subjects, seropositive for herpes simplex virus (HSV), underwent a standard course of broadband UV-B therapy, as used in the treatment of psoriasis. They received whole-body irradiation thrice weekly for four weeks with incremental doses dependent on skin type. Blood samples were taken immediately before, at two time points during, and at the end of the therapy. An HSV-specific CTL assay was performed using autologous B cells transformed with Epstein-Barr virus as targets. No consistent modulation in CTL activity was obtained as a result of the therapy. The CTLs were separated into CD4 and CD8 subsets by positive selection and, again, no effect of irradiation on CTL activity within each of these two populations was observed. In contrast, the natural killer (NK) cell activity, assessed by the lysis of K562 cells, was significantly reduced at the first time point after the initiation of the phototherapy in all five subjects, and it continued to decline as the treatment progressed. Thus a differential effect of UV-B exposure on cytotoxic activity has been demonstrated: the HSV-specific CTL response is unchanged, while the NK response is suppressed.

Up-regulation of human epidermal Langerhans' cell B7-1 and B7-2 co-stimulatory molecules in vivo by solar-simulating irradiation.

Ultraviolet (UV) radiation impairs cutaneous immune functions and induces antigen-specific tolerance both locally at the irradiated skin site, as well as at distant skin sites and systemically. It has been postulated that in the local model, altered Langerhans' cells (LC) provide tolerogenic signals, and studies in vitro have indicated that UV radiation may down-regulate the expression of co-stimulatory molecules on the surface of these cells. To examine the effect of UV radiation on LC co-stimulatory molecules in vivo, we irradiated human volunteers with erythematogenic doses of solar-simulating UV radiation (SSR), and analyzed the expression of cell surface markers in dermatome skin samples obtained 1-72 h post-irradiation. For flow cytometric analysis, epidermal cell (EC) suspensions were prepared and double labeled with monoclonal antibodies against CD1a or HLA-DR, and B7-1 (CD80), B7-2 (CD86), ICAM-1 (CD54), ICAM-3 (CD50), LFA-3 (CD58), E-cadherin, or integrin-beta4 (CD104). In unirradiated control skin samples, keratinocytes (KC) expressed high levels of E-cadherin. LC expressed high levels of both E-cadherin and ICAM-3, and low levels of B7-2, LFA-3, ICAM-1, and integrin-beta4. Following SSR, a triphasic reaction pattern was seen: an immediate, down-regulatory phase prevailing 2-6 h post-irradiation, when the number of DR+ and CD1a+ cells were temporarily reduced; a delayed, up-regulatory phase in which the number of LC was increased and the expression intensities of CD1a, HLA-DR, B7-1, and B7-2 were strongly up-regulated, maximally evident 12-24 h after irradiation, but no more seen at 48 h; and a late phase at 72 h, in which an influx of monocytes and a concomitant rise in DR+ cells was recorded. We conclude that to understand real-life cutaneous UV immunology, studies in vitro need to be complemented with studies in vivo. In the case of LC, the effects of erythematogenic UV radiation in vivo on human LC B7 co-stimulatory molecules include an up-regulatory stage.

Flow cytometric analysis of lymphocyte surface markers following a 1-Gy dose of gamma radiation.

Flow cytometric analysis of lymphocytes labeled with monoclonal antibodies was undertaken in order to compare the mean fluorescent intensity of several surface membrane antigens (markers) from irradiated and nonirradiated blood samples. Whole blood subjected to a 1-Gy (100-rad) dose of 1.25 MeV gamma radiation from a 60Co radioisotope source was compared with nonirradiated blood drawn simultaneously from the same healthy subject. Twenty runs were performed in which the following T and B lymphocyte and natural killer surface markers were analyzed: CD2, CD3, 13, CD4, CD29, CD45RA, CD8, CD56, and CD19. The data demonstrate a radiation-induced decrement in the mean fluorescent intensity of the high molecular weight markers CD45RA and CD56 (decrement is -3.3% and -7.2%, respectively). The statistical validity of these values was confirmed using paired t-tests, which yielded p values of p < 0.02 (CD45RA) and p < 0.01 (CD56). The fluorescent intensity is proportional to the number of intact binding sites on the lymphocyte surface and the observed decrement directly infers that damage to some sites occurred. These results illustrate a measurable effect on the lymphocyte membrane at a radiation dose at which many lymphocytes will survive, yet may be immunologically altered. This study may have important implications for personnel exposed to ionizing radiation, such as astronauts on long duration missions and radiation workers involved in accidental exposures.

Ultraviolet B-induced loss of HLA class II antigen expression on lymphocytes is dose, time, and locus dependent.

Ultraviolet B (UVB) irradiation interferes with the afferent and efferent loops of the immune response. One mechanism that has been suggested is the decline of class II histocompatibility antigen expression on the cell surface. However, data in the literature are controversial. In the present study, we examined the effect of UVB light (peak emission at 302 nm), at doses of 0.05-300 mJ/cm2, on class II antigen expression on normal peripheral blood lymphocytes enriched for non-T cells. Monoclonal antibodies directed at nonpolymorphic determinants on HLA-DR, -DQ, and -DP were used to label cells before and at time intervals up to 72 h after irradiation. Immediately following UVB exposure, fluorescence intensity for all three antigens was equal to or slightly increased above control values. Subsequently, there was a decline in antigen expression that was UVB dose dependent and varied for HLA-DR, -DP and -DQ. Although there was only a very moderate loss of surface labeling for HLA-DR up to 72 h, there was a steep decline for HLA-DQ and -DP. There was no significant decline in class II antigen expression on cells exposed to 2000 or 4000 cGy of gamma irradiation. Also, there was no effect of either gamma or UVB irradiation on class I antigen expression. These data explain some of the discrepancies in previous reports on the effects of UVB on class II antigens; they show not only a dose effect but also an effect of time after exposure and, most importantly, the class II antigen under study.

Rapid recovery of Langerhans cell alloreactivity, without induction of autoreactivity, after in vivo ultraviolet A, but not ultraviolet B exposure of human skin.

For therapeutic medical, cosmetic, and recreational reasons, humans expose themselves to increasing amounts of UVA. However, little is known of the photobiologic events associated with cutaneous carcinogenesis and photoaging that occur as a result of UVA exposure. UVB exposure of human skin abrogates the function of epidermal CD1+DR+ Langerhans cells and induces the appearance of CD1-DR+ non-Langerhans cell APC. This non-Langerhans cell APC population activates autoreactive immunoregulatory T cells that lead to suppressor-effector T cell function. In this report we show that, similarly to UBV, UVA exposure abrogates the function of CD1+DR+ Langerhans cells. However, in contrast to UVB, there is rapid recovery of Langerhans cell antigen-presenting cell activity and that CD1-DR+ non-Langerhans cell APC failed to appear to a significant degree. In keeping with the lack of CD1-DR+ epidermal cells, UVA exposed epidermal cells harvested 3 days after exposure functioned similarly to normal epidermis in that they activated alloreactive T cells but not autoreactive T cells in the absence of added Ag. This was in contrast to UVB irradiated epidermal cells that potently activate autoreactive T cells and contain CD1-DR+ cells. Thus, although both UVA and UVB initially depletes and inactivates CD1+DR+ Langerhans cells, the subsequent APC function of epidermal cells exposed to UVA differ profoundly from that of cells exposed to UVB. UVA radiation is less carcinogenic than UVB; differences in host responses to UV tumors may be linked to the rapid recovery of Langerhans cell function and the lack of induction of CD1-DR+ non-Langerhans cell APC after UVA exposure.

UV sensitivity of human keratinocyte and Langerhans cell-expressed HLA-DR antigens: a comparison.

HLA-DR expression on human keratinocytes (KC) was induced in vivo by intradermal injection of purified protein derivative of tuberculin (PPD). Neither preceding nor subsequent exposure of the PPD injection site to a dose of approximately 2 MED of UVB radiation abolished KC HLA-DR, though subsequent irradiation caused a slight diminution in the intensity of the antigen expression. By contrast, epidermal Langerhans cell (LC) HLA-DR and T6 expressions in normal epidermis were greatly reduced by an identical dose of UVB. Pemphigus antigen on the surface of KC was not affected by irradiation or PPD injection.

Effect of UVB radiation on the biosynthesis of HLA-DR antigens.

HLA-DR molecules on the surface of immunocompetent cells are thought to represent target structures for the immunomodulating effects of UV radiation during the induction of an immune response. We therefore investigated the effect of UVB radiation on the de novo synthesis of HLA-DR-gamma-chains in the cytoplasm and the expression of alpha- and beta-chains on the surface of the human lymphoblastoid B-cell line Raji. Raji cells were UVB irradiated before biochemical experiments were performed. Cells were then metabolically labeled or radioiodinated and detergent lysates immunoprecipitated using antibodies directed against the gamma- or the alpha- and beta-chain of the HLA-DR molecule. Over a wide dose range, UVB-irradiated Raji cells were shown to still express HLA-DR determinants on their surface and, even more importantly, to be capable of synthesizing HLA-DR-alpha, beta- and gamma-chains in a normal fashion. Despite this, the functional capacity of Raji cells was impaired in a dose-dependent manner. UV radiation thus seems to exert its immunomodulating effects primarily at a different level than the incriminated immune-response-associated antigens, which are expressed as recognition structures on the surface of immunocompetent cells.