Fatigue, serum cytokine levels, and blood cell counts during radiotherapy of patients with breast cancer.

PURPOSE: To assess the level of fatigue during the course of adjuvant radiotherapy (RT) of breast cancer patients and its relation to anxiety, depression, serum cytokines, and blood count levels. METHODS AND MATERIALS: Forty-one patients who received adjuvant RT after breast-conserving surgery were prospectively studied. All patients underwent RT without concomitant chemotherapy. Patients rated their fatigue with two standardized self-assessment instruments, the Fatigue Assessment Questionnaire and a visual analog scale on fatigue intensity, before RT, during weeks 1-5 of RT, and 2 months after RT completion. In addition, the anxiety and depression levels were assessed with the Hospital Anxiety and Depression Scale. A differential blood cell count and the serum levels of the cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha were determined in parallel to the fatigue assessments. RESULTS: Fatigue intensity as assessed with the visual analog scale increased (p <0.001) until treatment week 4 and remained elevated until week 5. Two months after RT, the values had fallen to the pretreatment levels. Fatigue measured with the Fatigue Assessment Questionnaire did not increase significantly during treatment, but the subscores on physical (p = 0.035) and cognitive (p = 0.015) fatigue were elevated during treatment weeks 4 and 5. Affective fatigue did not change significantly. Anxiety, as rated with the Hospital Anxiety and Depression Scale, declined during RT (p = 0.002), but the Hospital Anxiety and Depression Scale depression score did not change significantly. IL-1beta, IL-6, and tumor necrosis factor-alpha levels did not change during therapy and did not correlate with fatigue. Peripheral blood cell levels declined significantly during therapy and were still low 2 months after treatment. Until treatment week 5, lymphocytes were reduced to almost 50% of their initial values. Hemoglobin levels did not correlate with fatigue. CONCLUSIONS: We observed an increase in fatigue during adjuvant RT of patients with breast cancer. Fatigue returned to pretreatment levels 2 months after treatment. No evidence was found that anxiety, depression, serum levels of IL-1beta, IL-6, tumor necrosis factor-alpha, or declining hemoglobin levels were responsible for the treatment-induced fatigue.

[Radiation and burn trauma (combined injury). Considerations in surgical treatment]. / Das Bestrahlungs-Verbrennungs-Trauma (Kombinationsschaden). Uberlegungen zur chirurgischen Behandlung.

Combined injury syndrome (CIS) is defined as mechanical and/or thermal trauma associated with radiation injury. Each of these injuries is characterized by several systemic reactions, influencing especially the immune system and fluid balance. Experiences gained during World War II, the clinical observations after radiation accidents and experimental studies demonstrate that CIS can be considered as an own entity of disease characterized by increased mortality due to additive effects of the combined injuries. Up to now, our knowledge concerning the pathomechanisms of combined injuries is not sufficient. Nevertheless, there is a growing body of evidence that two basically different effects compromise organ function: (i) resembling or identical reactions of each trauma type simply added up to an increased systemic damage and (ii) posttraumatic alterations, where the effect of one kind of trauma synergistically increases the totally different effect of the other. Due to the associated acute radiation syndrome and the special pathophysiology of CIS, surgical treatment has to be considerably different from that of conventional multiple injured patients. Initial surgical procedures must be completed during the short time period of 48-72 h before onset of radiation-induced neutropenia and thrombocytopenia. This includes primary wound closure, management of all the abdominal, thoracical and vascular injuries as well as definite osteosynthesis. Later, all invasive procedures must be avoided due to the high risk of opportunistic infections and possible massive hemorrhage. When hematopoietic recovery begins, subsequent steps of surgical treatment can be taken into consideration. However, it is important, that as in conventional trauma, resuscitation and emergency care have priority and should be performed independent of the degree of radiation injury.

NF-kappaB and AP-1 are responsible for inducibility of the IL-6 promoter by ionizing radiation in HeLa cells.

PURPOSE: To investigate the mechanisms leading to initiation by ionizing radiation of IL-6 transcription in HeLa cells. MATERIALS AND METHODS: HeLa cells were irradiated with X-rays at a dose rate of approximately 1 Gy/min or treated with TPA (100 ng/ml). Transient transfection analysis with truncated IL-6 promoter CAT constructs was used to identify the radiation-sensitive region within the IL-6 promoter/enhancer. RESULTS: For basal expression of the IL-6 gene in unirradiated control cells the presence of the binding site for the nuclear factor kappa B (NF-kappaB) and the multiple response elements (MRE) were necessary. After deletion of either the activator protein (AP)-1 or the MRE site, radiation-induced IL-6 promoter CAT activity was significantly reduced, whereas after deletion of the NF-kappaB site it was completely abolished. Maximal radiation-induced IL-6 promoter CAT activity was observed when the AP-1, NF-kappaB and MRE motifs were present. In electrophoretic mobility shift analyses (EMSA), X-ray-inducible activity was found for NF-kappaB and AP-1 at the MRE constitutive, but no inducible activities were detectable. The nuclear factor IL-6 (NF-IL6) element showed no specific radiation-responsive activity. CONCLUSIONS: These results demonstrate that NF-kappaB plays a major role in X-ray-inducible IL-6 expression in HeLa cells. The fact that IL-6 promoter activity was dramatically enhanced in the presence of the MRE and distal AP-1 binding motif is indicative of a cooperative mode of transcriptional activation involving all three transcription factor systems. These data provide new insights into the prodromal events of radiation-induced inflammation of epithelial cells and putatively the cutaneous radiation syndrome.

DNA damage in human leukocytes after ischemia/reperfusion injury.

Leukocytes have been shown to play an important role in the development of tissue injury after ischemia and reperfusion (I/R). In the present study, the effects of tourniquet-ischemia on induction of DNA damage in peripheral leukocytes and on respiratory burst of neutrophils in humans were examined. The DNA damage was measured as increased migration of DNA using the single-cell gel-electrophoresis technique (comet assay). Intracellular production of reactive oxygen species by neutrophils was measured flow-cytometrically using dihydrorhodamine 123 as indicator. Postischemic, significantly increased migration of DNA was found in leukocytes of 20 patients (tourniquet-ischemia of the lower limb for 65-130 min, anterior-cruciate-ligament-reconstruction) and in 10 experiments (1 volunteer, repeated tourniquet-ischemia of the upper limb for 60 min, no operation). DNA effects were most pronounced 5-30 min after tourniquet release, and then declined over a 2 h period, but did not return to preischemic baseline values. A similar time course showed the oxidative status of unstimulated granulocytes during reperfusion. Simultaneously, opposing changes were measured in formyl peptide (f-MLP)- or phorbol ester (PMA)-stimulated granulocytes, which showed a significantly declined respiratory burst reaction after tourniquet-release indicating preactivation of neutrophils by IR. Our data suggest that IR induces genotoxic effects in human leukocytes presumably in response to oxidative stress during reperfusion.

Influence of clinically used antioxidants on radiation-induced expression of intercellular cell adhesion molecule-1 on HUVEC.

PURPOSE: The effects of antioxidants (N-acetyl-L-cysteine [NAC] and pyrrolidine dithiocarbamate [PDTC]) on radiation-induced ICAM-1 expression on human umbilical vein endothelial cells (HUVEC) were investigated. MATERIALS AND METHODS: The expression of ICAM-1 on HUVEC was determined by flow cytometry up to 72 h after X-irradiation. Functional competence of induced ICAM-1 was assessed by adhesion experiments with human polymorphonuclear neutrophils on irradiated HUVEC. RESULTS: Preincubation of cells with both or either NAC and PDTC was unable to reduce radiation-induced ICAM-1 expression on HUVEC. In fact, by themselves, these antioxidants induced a significant increase of ICAM-1 expression, which in comparison with a radiation dose of 7 Gy after 24h was nine times higher for PDTC, and more than double for NAC. Treatment with NAC clearly restrained TNF-alpha-induced ICAM expression on HUVEC, while preincubation of cells with PDTC showed synergistic effects. CONCLUSIONS: The role of reactive oxygen intermediates in signal transduction pathways leading to ICAM-1 expression should be investigated further. Furthermore, antioxidants may exert a pro-inflammatory role, as revealed by the induction of ICAM-1 expression on endothelial cells. The inhibition of TNF-alpha-induced ICAM-1 expression by NAC might have clinical implications because this substance is used as a radioprotector in radiotherapy.

Modulation of signal transduction pathways and global protein composition of macrophages by ionizing radiation.

It is assumed that the exposure of cells to ionizing radiation modulates their signal transduction pathways, which then govern the early and late radiation-induced alterations in gene expression. In this study we tested the effects of low doses of X-irradiation on the cell signaling and global protein composition of an HL-60 human promyelocytic leukemia cell line differentiated along a macrophage-like cell pathway by 4beta-phorbol-12-myristate-13-acetate (PMA). Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting of anti-phosphotyrosine immunoprecipitates, we found radiation-induced changes in the level of phosphorylation of proteins with molecular masses of 45 and 48 kDa, but in the most intensively stained area, ranging from 54 to 60 kDa, no alterations were observed. When two-dimensional electrophoresis (2-DE) immunoblotting was applied, only proteins from this heavily stained region were visualized and in addition the evident differences in tyrosine phosphorylated protein patterns between nonirradiated and irradiated cells were found in this area. Furthermore, the immunostaining of extracellular signal-regulated kinase 2 (ERK2) which did not prove its tyrosine phosphorylation demonstrated the existence of several ERK2 charge isoforms showing differential expression after X-irradiation. Comparing the whole protein profiles we found after the simultaneous quantitation of 1000 matched spots two proteins whose expression was regulated in an opposite manner in nonirradiated and X-irradiated cells. The quantities of both spots showed increases or decreases by a factor of 2 or more between irradiated and nonirradiated samples and both these changes were statistically significant (P<0.05).

[Systemic effect of extremity-ischemia reperfusion surgical trauma. Assessment of tourniquet ischemia induced activation of poplymorphonuclear neutrophic granulocytes]. / Systemische Auswirkung des Extremitäten-Ischämie-Reperfusions-Operations-Traumas. Nachweis einer Tourniquetischämie-induzierten Aktivierung polymorphkerniger neutrophiler Granulozyten.

Ischemia-reperfusion-injury represents a fundamental common pathway of tissue damage in a wide variety of disease processes, i.e. myocardial infarction, septic or hemorrhagic shock, multiple organ failure, trauma and organ transplantation. Ischemia-reperfusion-injury is said to be initiated by leukocyte accumulation and adhesion to vascular endothelium as well as oxygen free radicals playing a pivotal role in the pathogenesis of ischemia-reperfusion-injury. However, only few data exist for measuring influence of tourniquet-ischemia on the activation of granulocytes in humans. To assess the potential changes in activation of white blood cells immunophaenotyping (FacsScan, BD) of PMN was used in BTB-operated humans before and after 0, 5, 15, 30 and 120 min of tourniquet-ischemia of the lower and upper limb (no operation). We could show that tourniquet-ischemia (n = 20, 60-170 min) with operation significantly increased the CD 11b-expression to 149.5 +/- 73.4% (15 min after release of tourniquet, systemic, vs. bl: p < 0.05) and 160.1 +/- 55.1% (local, vs. bl: p < 0.001) and the CD 18-expression to 16.8 +/- 110.1% (systemic vs. bl: p < 0.01) and to 155.8 +/- 55.1% (local, vs. bl: p < 0.05). The tourniquet-ischemia of the upper limb without any operation (n = 10) induced an increase of the CD 11b-expression too (systemic, 149 +/- 76% and local 131 +/- 90%, both: p < 0.05 vs. bl). Furthermore there was a spontaneous release of free radical oxygen to 129.2 +/- 26.2% (systemic) und 154.8 +/- 35.9% (local: p < 0.01 vs. bl:) After stimulation by Phorbol-Myristat-Acetat (PMA) we demonstrated a decrease to 67.6 +/- 23.2% (systemic, p < 0.01 vs. bl) and to 68.3 +/- 15.6% (local, p < 0.01 vs. bl). These results indicate that ischemia-reperfusion-injury in humans induces a early measurable local and systemic activation of circulating PMN-granulocytes.

[Respiratory burst and phagocytosis activity in patients with infection after surgical abdominal interventions]. / Respiratory burst und Phagozytoseaktivität bei Patienten mit Sepsis nach abdominalchirurgischen Eingriffen.

Phagocyte functions such as respiratory burst or phagocytic activity allow the determination of septic courses. Already in case of surgical stress a reduced constitutive generation of reactive oxygen metabolites could be shown, which is assumed to influence the outcome of following septic courses. The results of septic patients suggest that in spite of a functioning uptake of particles and germs (phagocytosis) a defect of intracellular killing (respiratory burst) exists.

An immunological outcome predictive score for head and neck carcinoma patients.

AIM: To address the increasing demand for individualization of tumor therapy, a panel of immunological parameters was evaluated as potential early prognosticators for the outcome of treatment. PATIENTS AND METHODS: Thirty-one patients with advanced squamous cell carcinomas of the head and neck were treated either with a 2-course radiation treatment (60 to 70 Gy total dose) in combination with and subsequent to the administration of mitomycin C and 5-fluorouracil (radiochemotherapy) or with radiotherapy (2 patients) only. In 8 patients radio(chemo)therapy was preceded by surgical removal of the tumor. Before, during and after therapy, patients were immunophenotyped (in absolute numbers) and the respiratory burst function of granulocytes (polymorphonuclear [PMN] cells) was evaluated flow cytometrically. RESULTS: Before treatment a reduction of T and B lymphocytes to 64% to 81% of the means of 101 controls (healthy volunteers and hematologic normal patients) was observed, absolute PMN counts were increased by 31%, whereas monocytes and natural killer cells were not influenced. The helper (TH)/suppressor-cytotoxic (Ts/c) T cell ratio was significantly elevated. The respiratory burst reaction of the majority (74%) of patients was normal. During therapy all lymphocyte populations declined further as did the PMN counts. Natural killer cells were not significantly influenced while absolute monocytes increased significantly beyond normal levels after initial depletions during each course of treatment. The helper/suppressor ratio was reduced to normal levels. Overall, treatment resulted in systemic effects at the level of leukocyte subpopulations and appeared to cause a shift of immunocompetence to a predominantly monocytic system. The deficiency in the humoral immune system could be correlated with the short survival time of most patients. Based on early effects of the treatment (after 10 Gy), an immunological outcome predictive score could be defined. A simple mathematical combination of the changes of B and Ts/c cells (after 10 Gy vs. 0 Gy) together with the respiratory burst reaction of PMN prior to treatment allowed retrospectively to classify correctly 90% (17/19) of patients as survivors (> 120 weeks) or early deaths (< 96 weeks; p < 0.01). CONCLUSION: Single individual immunological data were not able to function as prognosticators for longer survival after therapy, but a combination of 3 parameters measured early during radio(chemo)therapy seems to allow the identification of "sensitive" patients. In how far the tumor disease per se and/or the immunological "sensitivity" are causes of death in these patients requires further clarification.

Differences in radiosensitivity of the respiratory burst generated in HL-60 cells via different signal transduction pathways.

Induced differentiation of the promyelocytic leukaemia cell line, HL-60, is associated with the acquisition of functional properties, like the expression of specific receptors and the competence to exert the respiratory burst (RB). In this system we evaluated the effects of ionizing radiation on the signal transduction processes involved in the activation of the respiratory burst/NADPH oxidase. HL-60 cells were X-irradiated with up to 1 Gy and induced towards granulocytic differentiation by treatment with 1.25% DMSO on day 0. The expression of the formyl peptide receptor (FPR), the development of responsiveness of the cells to its ligand (f-MLP) and to 4 beta-phorbol 12-myristate 13-acetate (PMA) were measured up to day 7 postinduction/irradiation. Using flow cytometry, fluorescinated formyl-hexapeptide or unlabelled f-MLP as ligands and dihydrorhodamine 123 (DHR 123) as an indicator of RB activity, respectively, the acquisition of functional responsiveness to both stimuli was determined. Immature FPR were identified at day 2 after induction which responded to the agonist from day 3 on. F-MLP receptor-mediated RB oxidase activation was completely radioresistant to 1 Gy, while protein kinase C (PKC)-stimulated triggering of the enzyme via PMA was inhibited by about 50% by 0.5 and 1.0 Gy. We conclude that different signal transduction pathways as triggered by f-MLP and PMA respectively exhibit differences in radiosensitivity, with PKC subspecies and downstream responses being possible sites of radiation damage.

Peripheral blood immune responses to surgically induced lung tissue injury.

Surgically induced lung tissue trauma reveals an immune response in peripheral blood, the degree of which could depend on extent and severity of the organ trauma and the presence of lung malignancies. The study included 34 patients who underwent elective thoracic surgery because of benign and malignant lung tissue diseases. Flow-cytometric phenotyping of lymphocyte subsets shows a clear shift to reduced immunocompetent cells after lung tissue injury. Patients with lung tumors reveal a postoperative activation of the macrophage system as indicated by increased plasma levels of neopterin. Increased levels of soluble interleukin-2 receptor in the plasma of these patients may be the result of cellular shedding of the receptor. Lung tissue trauma is also followed by reduced immunoglobulin levels which are most pronounced in the presence of lung malignancies. These results suggest that lung tissue injury leads to postoperative immunosuppression especially in tumor patients.

Proliferation kinetics and PCNA expression of HL-60 cells following ionizing irradiation and granulocytic differentiation.

The human promyelocytic leukaemia cell line, HL-60, was investigated with regard to proliferation and terminal differentiation following irradiation. The cells were X-irradiated and induced with 1.25% dimethyl sulfoxide (DMSO) towards the granulocytic lineage. Proliferation was measured via cell growth, clonogenicity and the bromodeoxyuridine/DNA incorporation assay. Immunohistochemical detection of proliferating cell nuclear antigen (PCNA) expression was used to discriminate cycling from non-cycling cells. The differentiation obtained was proved by testing for the immune function of the respiratory burst (NBT reduction test). The HL-60 cells studied revealed a high radiosensitivity (D0 = 0.63 Gy). After induction with DMSO, declines in cell growth, clonogenicity and PCNA positivity of the cells indicated a decrease in proliferation and an increase in differentiation. Starting on day 2 in culture, irradiation after seeding with 1 Gy accelerated the loss of the PCNA expression in induced cells (46% v. 3% PCNA-negative control cells on day 3). Induced cells gained the capability of exerting the respiratory burst, which was found to be dose-dependent radiosensitive (42%, and 12% NBT-positive cells after 1 and 2 Gy, respectively, v. 53% NBT-positive control cells on day 8). Subpopulations in the cell line were evident in all parameters investigated. We discuss the HL-60 cell, not only as a model comparable to human progenitor cells, but also as a suitable tool in radiobiological research with regard to proliferation and differentiation following ionizing irradiation.

Fluorescence instability of propidium iodide-labelled microspheres in (para)formaldehyde.

An instability of the fluorescence of propidium iodide (PI)-labelled microspheres was observed when the beads were used as an internal fluorescence standard in cell samples suspended in paraformaldehyde (pFA) for flow cytometric phenotyping. Flow cytometry of fluorochrome-labelled microspheres as well as spectrofluorometry of PI-fluorochrome solutions in PBS-buffered 1% pFA or formalin (FA) revealed strong increases of PI fluorescence starting immediately after the addition to the fixatives. We propose a chemical reaction which leads to two additional conjugated double bonds in the modified fluorochrome causing the increased fluorescence emission. Therefore, PI-labelled microspheres should not be applied as internal fluorescence references in aldehyde-containing cell suspensions for flow cytometric analysis, except when the time interval between the addition of beads and the measurement can be kept constant or if it lasts longer than 1 h.

The respiratory burst of neutrophils, a prognostic parameter in head and neck cancer?

Flow cytometric measurements of the respiratory burst of granulocytes (PMN) from 27 patients with advanced carcinomas of the head and neck revealed two types of responses to a stimulus with phorbol myristate acetate (PMA) before, during, and after radiochemotherapy. (1) The majority (74%) of patients responded quantitatively normal (31-fold increase of fluorescence intensity after PMA stimulation, as in controls) but exhibited functional subpopulations in 63% of samples with varying degrees of hyperreactive PMN. (2) A subgroup of 7 patients did not respond to PMA before and during treatment ("nonresponders"), but in two cases responded after therapy. Survival analysis revealed a significantly (P less than 0.02) decreased mean survival time of nonresponders (36 weeks vs greater than 70 weeks in "responders"). Thus, the respiratory burst of PMN could serve as a prognostic parameter in head and neck cancer.

Comparison of micronucleus frequencies and proliferation kinetics in three X-irradiated cell lines.

The kinetics of the occurrence of micronuclei was correlated with the survival of three mammalian cell lines of human, monkey, and mouse origin after irradiation with 240 kV X-rays. Particular attention was paid to the evaluation of the individual proliferation kinetics of the cell lines as well as to the characterization of micronuclei subpopulation with respect to size and possible biological importance using DNA and BUdR labelling techniques, fluorescence microscopy, and image analysis. The results demonstrate very characteristic size distributions of micronuclei for the three cell lines independent of radiation dose and time after irradiation. A close correlation between cell death and the occurrence of micronuclei (expressed as a calculated "MN index") after irradiation could be established only when the kinetics of progression of cells through the cell cycle (e.g. the doubling time) and the biological characteristics of micronuclei (e.g. BUdR positivity, the micronucleus frequencies, and the number of micronuclei per main nucleus) were taken into account. Therefore, the micronucleus assay might not be useful as a quantitative predictive assay in vivo but may allow qualitative estimations of radiation damage only because the necessary proliferation parameters of the cells might not be possible to establish in vivo.

In vitro synthesis and processing of pre-rRNA in isolated macronuclei from Tetrahymena.

Macronuclei were isolated from logarithmically growing Tetrahymena cells in isoosmotic medium containing the weak detergent n-octanol and were purified in sucrose gradients. Electron microscopy revealed good structural preservation including intact nuclear envelopes. Initial rates of [3H]UTP incorporation into these nuclei were relatively high (2-4 pmol UMP/micrograms DNA per min), and 70 to 80% of transcription was resistant to alpha-amanitin, which is similar to the percentage of nuclear label associated with the nucleoli in electron microscopic autoradiograms. The use of transcription initiation inhibitors indicated that elongation of in vivo initiated pre-rRNA chains had essentially occurred in vitro. The radioactivity profiles of in vitro synthesized RNA in gels exhibit a heterogeneous pattern with the exception of a small peak corresponding to the length of pre-rRNA molecules. Detailed analysis of the extent and specificity of pre-rRNA processing was performed by RNA transfer hybridizations using cloned rDNA fragments as probes. The results show that the early processing events, i.e., splicing, 5'terminal and central cleavage of pre-rRNA, proceed faithfully, but at reduced rates and efficiencies. Furthermore, processing of pre-17S rRNA at the 3'end, and pre-26S rRNA at the 5'end, including the formation of immediate 5.8S rRNA precursors (ITS and 7S RNA), occurred. In contrast to previous in vivo results, a central hidden break was also introduced into part of nuclear 26S rRNA molecules. In addition to the known intermediates and by-products of processing, a large number of distinct fragments due to non-random cleavages of rRNA precursors appeared during in vitro incubation of macronuclei. Most prominent were two novel small RNA fragments from the 5'terminal end of pre-rRNA which may be products of alternative processing sites in the external transcribed spacer. Another small promoter-proximal RNA which is present in substantial amounts in vivo, was not formed under in vitro processing conditions, but degraded rapidly. This is further support to the notion that this RNA species may represent a product of premature transcription termination.

Flow cytometric characterization of rat thymus cells in a radiation-dominated model of combined injury.

Thymuses of rats that had been: a) gamma-irradiated [500 cGy whole-body radiation (R)], or b) thermally injured [20% BSA dorsal, scald burn (TI)], or c) combined injured [irradiation followed by burn (CI)] were studied for involution and recovery processes after sublethal treatments. The expression of surface antigens on thymic cells before and after injuries was evaluated using the monoclonal antibodies (mcAB) MRC OX4, MRC OX7, MRC OX8, W3/13 HLK, and W3/25 and flow cytometric analysis. Thymic cellularity decreased to less than 1% of normal (N), age-matched rats by 4 days after R or CI. Recovery reached 60% to 70% of N by 28 days post treatments. TI caused a biphasic thymic recovery pattern with nadirs of 40% of N on days 7 and 21. Recovery at day 28 was similar to that after R and CI. Expression of OX7, OX8, W3/13, and W3/25 antigens all reached nadirs of 40% of N by day 4 after R and CI. Recovery of antigen expression, except for W3/25, was near completion by day 7 after R and CI. Changes in antigen expression after TI were less pronounced for all mcAB tested. Decreases in labeling of thymocytes with the helper T-cell marker, W3/25, observed after TI, could not be correlated with elevated expressions of the suppressor/cytotoxic T-lymphocyte antigen, OX8. Variations in relative labeling of nonlymphoid thymic cells with OX4 (Ia-antigen) reflected the disappearance and recovery of radiosensitive lymphoid thymocytes. The similarity of results after R and CI demonstrate that the model of CI is 'radiation-dominated.' The addition of burn injury to radiation trauma had no synergistically damaging effect on the parameters studied.

Rat monocytes in a model of combined injury express the OX8 antigen.

We have analyzed peripheral blood mononuclear cell preparations from a rat model of combined injury (CI) [whole-body irradiation (500 cGy 60Co) followed by a thermal injury (20% body surface area, dorsal, scald burn)] for the expression of OX8 antigens. Ficoll-separated mononuclear fractions were labeled with monoclonal antibodies MRC OX8, MRC OX19, W3/13 HLK, or W3/25 for flow cytometric analysis. Combined-injury trauma resulted in decreased mononuclear cells to 6% of normal. This effect was due to the rapid decrease in radiosensitive lymphocytes from 83% to 10%. The relative numbers of monocytes increased from a normal 13% to 70% at day 4 after CI. Labeling of cells with OX8 after CI shifted to a population which was significantly larger in volume than normal lymphocytes. At the same time the mean fluorescence intensity of OX8-positive cells was considerably reduced. With the use of a F(ab) fragment of OX8 as a probe, these results could be partially explained as unspecific binding of the whole molecule of OX8 to Fc receptors expressed by activated monocytes. But double-labeling and cell-sorting experiments also revealed the expression of OX8 antigens by a subset of OX8+/OX19- monocytes after CI.