Inhibition of leukocyte chemotaxis by factor in alloxan-induced diabetic rat plasma.

The early local exudative cellular reaction in an inflammatory lesion was impaired in alloxan-induced diabetic rats due to reduced migration of neutrophils to the inflamed area. Neutrophils, however, were capable of moving from reserve compartments into blood in these animals. Furthermore, the functional integrity of their surface membranes, assessed by the capacity of the cells to adhere to nylon fiber, was not altered by alloxan diabetes. An intrinsic cellular defect also did not occur, because the cells were capable of responding to chemotactic stimuli in the Boyden chamber system, provided they were suspended in Eagle's medium or normal serum. Suspended in the corresponding diabetic serum, a blockade of the chemotactic response was observed. Increasing concentrations of diabetic serum, added to a suspension containing neutrophils collected from normal donors, progressively inhibited the response of the cells to a chemotactic stimulus. Hyperglycemia alone or hyperosmolality secondary to hyperglycemia, the presence of ketone bodies, or a direct effect of alloxan did not explain the results. In addition, the capacity to generate chemotactic factors remained intact in diabetic serum. Pretreatment of the diabetic animals with insulin resulted in a gradual recovery of the chemotactic response in vivo and in vitro. We conclude that alloxan-induced diabetic rat serum contains a substance that inhibits neutrophil chemotaxis and that insulin administration is essential for the clearance of this substance from plasma.

Lymphocytes in non-immune inflammation: a specific subclass of lymphoid cells?

Rats were subjected to various experimental procedures which affected lymphocyte numbers, in an attempt to investigate the participation of individual subpopulations of these cells in the development of acute, non-immune inflammation. Deficient T function, as evidenced in neonatally thymectomized animals, or in 6-week-old animals thymectomized and afterwards exposed to multiple total-body X-ray irradiations, did not interfere with the development of the acute inflammatory responses of the animals to carrageenin. In the former circumstance, the numbers of circulating B lymphocytes, identified by the presence of surface immunoglobulins, were increased. In thymectomized and irradiated rats, the B-lymphocyte subpopulation was reduced. Circumstances causing attenuated inflammatory reactions to carrageenin resulted, first, from lymphocyte depletion by chronic drainage from the thoracic duct and, second, from irradiation of the animals with a single large dose of X-ray, the animals being tested 24 h after irradiation. B lymphocytes in blood remained within the normal range after chronic lymphatic drainage, but a large dose of X-ray markedly reduced their number. In both cases the attenuation of the responses to carrageenin did not seem to be associated with nonspecific hyporeactivity, or with the effect of the treatments on the other blood cells, It is suggested that the development of acute, non-immune inflammation is influenced by lymphoid cells which might constitute a specific subclass of cells, distinct from fully differentiated T and B lymphocytes.

Participacao da histamina em processos fisiopatologicos. / The participation of histamine in physiopathology processes

A biossintese, distribuicao, armazenamento e propriedades farmacologicas da histamina, bem como o envolvimento em processos fisiopatologicos sao considerados. Indicam-se as evidencias de sua participacao nos fenomenos alergicos e anafilaticos, nas respostas inflamatorias inespecificas, na natureza pigmentosa e mastocitose e na etiopatogenia da ulcera peptica

The inflammatory responses of rats depleted of lymphocytes or with an artificial obstruction of the thoracic duct.

Rats selectively depleted of lymphocytes by chronic drainage from the thoracic duct during a 3-day period presented a marked lymphopenia, and decreased responses to carrageenin injected into one of the hind paws. The intensity of the inflammatory responses in thse animals was restored by the i.v. administration of suspensions of viable or lysed lymphocytes, collected from the spleen or lymph of normal animals. A spontaneous reversal of the depressed responses to carrageenin was observed 40 days after the period of lymph drainage, when lymphocyte counts were again normal in blood. If highly inbred rats were used, the i.v. injection of syngeneic lymphoid cells was equally effective in restoring the inhibityed inflammatory responses resulting from lymphocyte depletion. Artificial obstruction of the thoracic duct, with interruption of lymphocyte recirculation, was followed by decreased lymphocyte counts in blood and severely depressed inflammatory responses to carrageenin. This unresponsive state was corrected as the animals recuperated, probably coincidentally with the development of collateral lymph channels and as the temporarily disturbed blood picture returned to normal. It is concluded that lymphocytes can participate in the development of non-immune inflammation through the release of pro-inflammatory factors. This release is independent of previous sensitization of the cells.

Sensory nerves and inflammation: evidence for the release of a neurogenic permeability factor by tityustoxin.

Venom of the scorpion Tityus serrulatus and its active principle tityustoxin (TsTX), kept in contact with the peripheral cut end of the sciatic or saphenous nerve of the rat, induced inflammatory reactions in the areas supplied by the nerves. The reactions include increased vascular permeability and oedema formation below the tibio-tarsal articulation, and were similar to those evoked by electrical antidromic stimulation of these nerves. When electrical stimulation of the peripheral nerve ending preceded its contact with the toxin or, conversely, when the application of electrical pulses closely followed contact with TsTX, no marked increase in the vascular permeability and oedematous respones, subsequent to the second stimulation, was observed. Anti-histamine and anti-serotonin drugs, as well as substances capable of blocking synthesis of prostaglandins or activation of the kinin system, and also atropine, were ineffective in reducing the responses to TsTX or electrical stimuli. Since the responses were evoked at a distance, in the areas supplied by the nerves, they must be chemically mediated. It is concluded that TsTX and electrical antidromic stimuli affect sensory nerves inducing the release of a permeability-increasing factor, which is responsible for the observed reactions. This factor can be depleted from storage sites by prolonged stimulation of the nerves, is not inhibited by antagonists of known mediators of inflammatory reactions and most probably originates in sensory fibres.

The proinflammatory function of lymphocytes in non-immune inflammation: effect of steroidal and non-steroidal anti-inflammatory agents.

Leucopenia rendered rats unresponsive to various inflammatory stimuli. The intensity of the inflammatory response in such animals was restored by i.v. administration of suspensions of lymphocytes, but not of granulocytes. This restorative effect was blocked by both steroidal and non-steroidal anti-inflammatory drugs. Utilizing carrageenin to induce inflammatory responses in the rat's paw, the effect of these drugs on lymphocytes was observed in two circumstances. First, following incubation of the cells with the drugs in concentrations not exceeding the peak plasma levels estimated for these substances in man or laboratory animals; the effect of the drugs seemed selective, since anti-histamine and anti-serotonin agents, as well as amethopterin, were devoid of action. Second, when lymphocytes were collected from rats previously treated with the various anti-inflammatory agents, injected 6-hourly during periods of 18 and 36 h, respectively, for steroidal and non-steroidal anti-inflammatory substances. The total amounts given were lower than those required to produce consistent anti-inflammatory effects in normal animals, when the drug was given as a single dose before injection of the irritant. It is concluded that the pro-inflammatory function of lymphocytes in non-immune inflammation can be blocked by steroidal and non-steroidal anti-inflammatory agents.

Participation of sensory nervous structures in the development of inflammatory reactions.

The participation of sensory nervous structures in the development of inflammatory responses in the rat's paw was investigated. Electrical antidromic stimulation of the saphenous or sciatic nerves during 20 min produced an oedematous response in the paw and potentiated the reaction to locally injected carrageenin. On the other hand, decreased responses to carrageenin were observed either when the sciatic nerve was sectioned 15 days before or when a prolonged electrical stimulation (45 min) of the nerve preceded by 1 h the injection of the irritant into the paw. However, if the sciatic nerve was sectioned 30 days before, the inflammatory response to carrageenin in this paw was equivalent to that observed in the contralateral, intact paw. It is suggested that sensory nervous structures might contribute to the development of inflammatory responses, through the release of an active agent, probably from neural origin. This agent would be depleted by prolonged stimulation of sensory nerves. Following partial denervation, the remaining sensory nervous structures in the affected area might develop compensatory mechanisms to influence the institution of the reaction.

Decreased vascular reactions to permeability factors in experimental diabetes.

Light and electron microscopic studies showed that blood vessels of the cremaster muscle of alloxan-diabetic rats under the local influence of histamine or serotonin presented less labelling by colloidal carbon, previously injected i.v., than vessels of normal rats. The hyporeactive state of these vessels was promptly reversed to normal conditions by the administration of insulin. Insulin also potentiated leakage of carbon particles in the vessels of normal animals. These findings add new evidence that insulin might be involved in vascular events following injury and that decreased levels of the hormone, as occurring in diabetes, might result in decreased inflammatory reactions.

Does the pro-inflammatory factor in lymphocytes (LpIF) explain the role of these cells in acute inflammation?

Lymphocytes produce a pro-inflammatory factor, which modulates the development of acute inflammation. Injection of lymphocytes or products, obtained from either rats, dogs or rabbits, caused a restoration of inflammatory responses in leukopenic rats which are hyporeactive to various inflammatory stimuli. In vitro incubation of viable lymphocytes with homologous and heterologous anti-lymphocyte sera abolished the ability of the cells to restore the inhibited inflammatory reactions.

Modulation by lymphocytes of the vascular effects caused by inflammatory mediators and carrageenin in the rat.

Inhibited permeability responses to intradermally injected histamine, serotonin and bradykinin were observed in leucopenic rats, when compared to those measured in normal animals. Significant reversal of the inhibited responses was seen when leucopenic rats were given suspensions of lymphocytes i.v. Suspensions of PMN granulocytes, however, were ineffective. In both cases, the volumes of the suspensions contained adequate quantities of the particular cells to counteract their deficiency. Histological changes provoked by carrageenin in the paws of leucopenic rats injected with suspensions of lymphocytes resembled those of normal rats, the main difference being that the number of cells which had emigrated into the affected tissues was reduced. In leucopenic controls or leucopenic animals injected with suspensions of PMN granulocytes, minimal histological alterations were observed. It is concluded that lymphocytes play a role in the development of acute inflammatory reactions.

A proinflammatory factor in lymphocytes. Its role in the development of acute, non-immunological inflammatory reactions.

Drug-induced leucopenia renders rats hyporeactive to various inflammatory stimuli. Administration to leucopenic rats of suspensions of lymphocytes, sufficient to apparently correct the induced lymphocytopenia, led to a partial but marked reversal of the inhibited responses. Similar results were observed when lysates of lymphocytes or filtrates of the disintegrated cells were injected. Suspensions of polymorphonuclear granulocytes, on the contrary, were ineffective in producing a reversal of inhibited inflammatory reactions in leucopenic rats. The presence of a proinflammatory factor (LpIF) in lymphocytes, which might be involved in the modulation of acute inflammatory responses is suggested.

The effects of adrenalectomy and corticosterone on vascular permeability responses in the skin of the rat.

The vascular permeability response induced in the rat by intracutaneous histamine or serotonin is noticeably influenced by previous adrenalectomy or treatment with corticosterone. Permeability responses were demonstrated by the local exudation of circulating Evans blue at sites of intracutaneous injection of the above permeability factors, the intensity of the responses being assessed by the diameter of the blue lesions as well as by the amount of exuded dye. In adrenalectomized rats maintained for 72-80 h on 0-9% solution of NaCl, the permeability response to histamine was enhanced about 10-fold, that to serotonin about 5-fold. When rats were given subcutaneous corticosterone, 1-0 mg/animal 1 h before testing, the responses to the same 2 permeability factors were decreased about 10-fold and 5-fold respectively. Corticosterone also decreased the enhanced responses in adrenalectomized rats to levels somewhat below those in mock adrenalectomized controls. The results support the proposal from other work that vascular exudation in experimental inflammation is regulated by an anti-inflammatory factor that accumulates in injured tissues and owes its effect to release of corticosteroids.

In vitro and in vivo release of histamine by contrast media in the rat.

Some contrast media are able to release histamine from isolated mast cells of the rat and produce degranulation of these cells. Such properties are fairly correlated with the ability to increase vascular permeability in vivo and to produce a drop in blood pressure. If histamine is similarly being released in humans many untoward effects of these agents referred to clinically might be thus explained.

Stimulation of the hypothalamo-pituitary-adrenal axis by compounds formed in inflamed tissue.

1 Rat paws were injected with carrageenin, and their subcutaneous tissue perfused 135 min later. These perfusates were injected intravenously into receptor rats in which they caused an attenuation of inflammatory responses. 2 The effect was not observed in adrenalectomized receptor rats nor in receptors with electrolytic lesions in the median eminence of the hypothalamus but persisted in adrenal-demedullated animals. 3 The active perfusates also induced eosinopenia in normal or adrenal-demedullated animals, but not in adrenalectomized rats, and produced an increase in blood corticosterone with a concomitant decrease in the amounts of adrenal ascorbic acid. 4 The active perfusates did not affect the responses of isolated preparations to histamine, bradykinin, prostaglandins and 5-hydroxytryptamine neither did they elicit changes of the arterial blood pressure in receptor animals. 5 The anti-inflammatory activity present in perfusates from inflamed paws seems to be formed slowly at the site of the developing inflammatory reaction, since perfusates collected 30-65 min after the injection of carrageenin were ineffective, as was plasma taken from donor rats at various time intervals after carrageenin injections. 6 It is suggested that the anti-inflammatory factor present in the active perfusates exerts its action by stimulation of the hypothalamo-pituitary-adrenal axis.