Thermal injury: release of a cytotoxic factor

A recombinant anti-ICAM-1 Fab fragment is as effective as the complete IgG antibody in treatment of burns in rabbits

The purpose of this study was to examine the efficiency of an Anti-ICAM-1-Fab fragment in the treatment of burns. Blocking ICAM-1 using murine IgG with the purpose to prevent further damage to the zone of stasis has proven its effectiveness in animal models as well as in humans. The use of murine Antibodies has some disadvantages including allergic reactions and complement activation. For the first time we examined an industry produced Fab-fragment blocking ICAM-1 and compared it to the corresponding IgG antibody. We showed in a standardised rabbit burn model that an Fab-fragment is capable of blocking ICAM-1 and therefore improving the reaction of the skin to trauma in the zone of stasis.

Impairment of splenic B and T lymphocytes in the early period after severe thermal injury: immunohistochemical and electron microscopic analysis

Immunocompetent cells, such as lymphocytes and macrophages are easily damaged after severe thermal injury. In the present study, we investigated structural changes in splenic lymphocytes in the early period after a full skin thickness burn of 30% of the body surface area in rats. At 2h after thermal injury, numerous B lymphocytes had accumulated in the markedly expanded marginal zone of the splenic white pulp. Electron microscopy showed a small number of apoptotic cells in the marginal zone of the white pulp. After 5h, B lymphocytes in the marginal zone as well as in the lymphoid sheath and follicles were markedly decreased in number with an increase of tingible bodies and tingible body macrophages. The number of apoptotic cells had increased not only in the marginal zone, but also in the lymphoid sheath and follicles. After 12h, the splenic white pulp became atrophic with the appearance of a small number of large blastic cells and mitotic figures. After 24h, the splenic white pulp was still atrophic with a decrease in the number of lymphocytes, especially B lymphocytes. On the other hand, the large blastic cells and mitotic figures increased in number. Apoptotic cells decreased in number in the white pulp. After 48h, the lymph follicles were slightly enlarged and a small germinal centre occasionally appeared. A small number of T lymphocytes were observed in the splenic white pulp of the normal rats. However, the T lymphocytes almost disappeared shortly after thermal injury. A recovery in T cell number was observed only after 48h. These findings indicate that severe impairment of both B and T lymphocytes, circulating and in the lymphoid organs, occurs shortly after thermal injury and continues for several days. This severe damage to the lymphocytes is considered to be closely related to severe immune suppression after thermal injury.

The cellular response of T and B dependent areas of the spleen after focal thermocoagulation of liver and kidney

Using 3H-thymidine autoradiography, the cellular response of the white splenic pulp after single or repeated thermolesions on liver and kidney was studied. Sham operations served as controls, and did not induce any significant changes in the splenic white pulp. After single or repeated thermolesions, the labeling index increased distinctly in the B and T cell areas. The central T-dependent periarteriolar lymphatic sheath (PALS) showed an earlier rise of radioactively labeled lymphocytes after repeated thermolesions than after a single lesion. After a single heat coagulation of liver and kidney a dissociation of the germinal centers occurred with consecutive hyperplasia. However, compared with the splenic reaction after other surgical injuries, especially after cryosurgical operations, the response of the B-dependent splenic areas was weaker. The distinct reaction of the central T-dependent PALS supports the conception of a more prominent cell mediated immune response of the peripheral lymphatic system with temporary T cell dysfunctions. Possibly the inflammatory complications of burned patients and the delayed wound healing of thermosurgical tissue lesions may be caused by the alteration of the lymphatic system with a disturbed cooperation of T and B lymphocytes with macrophages.

DNA-synthesis in the rat thymus after focal thermolesions on abdominal organs

The changes in the DNA-synthesis of lymphocytes in the different zones of the rat thymus were autoradiographically studied with 3H-thymidine after focal thermonecroses (740 degrees C/4 sec) on abdominal organs and sham operation (laparotomy). A single thermolesion was performed in separate groups of rats on the liver and spleen, whereas a third group received multiple heat lesions (liver, kidney, stomach wall). A slight decrease of the labeling index occured during the first 36 h after the sham operation and was attributed to an unspecific stress effect leading to an increased release of corticosterones. The most remarkable and contrasting result was the observation that after thermonecroses a decrease of the labeling index of thymus-lymphocytes did not happen during the first 48 h but rather a marked increased with a maximum on the fifth day. It was concluded that the stimulated DNA-synthesis in the thymus might be related to a cell mediated immune response against thermocoagulated tissue components or to an immediate T-cell dysfunction, which is known to develop after burns. In both cases the thymus might react with an increased division and maturation of lymphocytes regulated through a feed-back mechanism.

Isolation of a protease from the cell-free medium of in vitro cultured mammary carcinoma

Trypsin-like protease with wide spectrum of enzymatic activities have been isolated from cell-free medium from in vivo cultured human mammary carcinoma cells, and from peripheral blood lymphocytes of patients with mammary carcinoma cultured in presence of cell-membrane carcinoma-associated glycoprotein.

Kidney tubular cell proliferation in burned mice

Kidney tubular cell proliferation after a 17%, sublethal, third-degree burn injury in mice was studied in vivo using tritiated thymidine. Changes in cell morphology were also followed. Total incorporation of 3H-TdR in renal cells was measured and autoradiographic analyses of the tubular cells in the renal cortex and in the stratum subcorticale were made 2 hours to 30 days after the injury. After the second day postburn there was a 3.5-fold stimulation in the total incorporation of 3H-TdR in DNA, and an 18-fold increase in the labelling index of tubular cells. The majority of the labelled cells were proximal tubular cells. After the third day postburn a moderate increase in the labelling index (7.5-fold) was observed; 40% of the labelled cells were distal tubular cells. No morphological signs of frank necrosis of the tubular cells could be observed in the burned mice within 3 days postburn, which indicates that the stimulated proliferation of the kidney tubular cells was induced by minor reversible tubular cell damage during the first few hours postburn. It is suggested that the tubular cells loose their normal growth-inhibiting factors through an altered cell wall which results in an abnormal stimulation of cell growth 2 days later. These findings support the idea that there are abnormalities in the regulation of cell growth in several organs after burn injury; in some tissues--as in the kidney--this results in a temporary insufficiency of organ function.