Antibacterial immunity of lower airways: local or localized?

Clearance of bacteria in the bronchoalveolar lavage, the level and functional activity of IgA and changes in the cellular composition of BAL were examined in mice after supralaryngeal immunization and subsequent challenge with Klebsiella pneumoniae. More than 60% of the bacterial inoculum was removed by nonspecific mechanisms within 90 min after inoculation; within the time interval 1.5-3.5 h, clearance was significantly accelerated in locally immunized mice. The enhancement of clearance effectiveness is specific and increases proportionally with the length of immunization (1 less than 2 less than 4 weeks); it is of short duration and towards the end of the 3rd week after immunization, in 73% of immunized animals, the clearance values did not differ from values found in controls. The local immunization did not influence the total level of IgA in BAL, the formation of specific IgA antibody was minimal, in vivo binding of IgA to klebsiella could not be demonstrated. In immunized mice, a significant increase in the numbers of PMN and lymphocytes, as well as an increased activity of phagocytic cell (PMN, MP) was found in BAL. The time interval of 1.5-3.5 h after challenge bounds the space for mechanisms, activated by local immunization in lower airways. The actual participation of individual factors in the accelerated elimination of bacteria from the lumen of airways, remains unclear so far.

Mechanisms of antibacterial immunity of mucous membranes.

A survey based on both literary data and the authors own results, concerning the mechanisms of sIgA-mediated antibacterial immunity, is presented. Secretory IgA is characterized as a specific component of the immune system of mucous membranes, which can recognize harmful bacterial and distinguish them from indigenous microflora physiologically colonizing the mucous membranes, to fix them to the mucous membrane surface and to direct further factors, such as mucin, lysozyme, etc. (which form the effector component of the mucous membrane immunity system) for their final inactivation and neutralization.

Modification of Oudin's method of single immunodiffusion in agar gel for detection of IgA in bronchoalveolar lavage of white mice.

Oudin's principle of single immunodiffusion in agar gel was modified for quantitative determination of IgA in bronchoalveolar lavage (BAL) of normal 20-25 g mice. The reaction took place at 25 degrees C in 0.3% agarose with 16.7% pig serum against mouse IgA, and was evaluated on the basis of a relationship between the progress of the precipitin zone and the square root of time. The linear dependence of the derived constant k on the logarithmic concentration of antibody in the sample permitted to express the results as titre, corresponding to a dilution where k = 0. Examination of seven samples of pooled blood serum of normal mice showed that (1) the IgA level was practically constant, (2) serum IgA possessed under given conditions similar properties as IgA from the bronchoalveolar secretion; it is therefore possible to employ pooled sera as a reliable control of the immunodiffusion system in case of lack of reference standards with defined IgA content. Examination of 82 individual BAL samples of normal mice revealed that the mean IgA concentration in 2.5 mL samples was almost 1000 times lower than in blood serum.

Experimental model of Klebsiella infection in mice for studies on mechanisms of local immunity of the respiratory tract.

An experimental model in white mice, infected with a mildly virulent strain of Klebsiella pneumoniae, was elaborated for studies on local immunity of the respiratory tract. Instillation of klebsiella into the supralaryngeal space of anaesthetised animals proved to be more suitable than the commonly used method of intranasal infection. The strain administered by the supralaryngeal route, persisted in the lungs of most mice at approximately equal level 1 d after infection, in some animals it could be demonstrated even after 2-3 d. Using this model (based on various rates of lung clearance), one can demonstrate faster elimination of klebsiella after a local (supralaryngeal) than systemic (intraperitoneal) immunization with a heat-inactivated vaccine, prepared from a homologous strain of K. pneumoniae.

Substance P levels in the rat forebrain after apomorphine and haloperidol treatment.

The content of substance P(SP) in the rat forebrain was assayed by radioimmunoassay technique after apomorphine and haloperidol injection. Apomorphine (1 and 10 mg/kg) produced dose-dependent decrease in SP content, while haloperidol, 0.2 and 1 mg/kg produced a marked increase in SP level in the forebrain. The results may suggest a modulatory role for SP in the action of dopamine receptor agonists and antagonists.

Lack of postulated opiate-receptor antagonistic properties of compound 48/80.

The previously suggested opiate-receptor antagonistic properties of compound 48/80 were checked both in vivo and in vitro. In electrically stimulated guinea pig ileum and rat vas deferens preparations compound 48/80 did not reverse the inhibition of the twitches caused either by morphine or Met5-enkephalin. In mice hot-plate test compound 48/80 did not decrease the analgesic activity of morphine. In radioreceptor studies compound 48/80 shows rather low affinity to the 3H-naloxone receptor sites from striatal homogenates of the rat, as compared to non-labelled naloxone and on the other hand it produced moderate, as compared to d-butaclamol, displacement of 3H-spiroperidol from rat striatal homogenates. The variation of composition of various polymers making compound 48/80 is suggested for explanation of obtained results.

Effect of opiates on the caudate spindle in the cat.

The effect of opiate drugs on the caudate spindle (CS) in the cat was observed following both systemic and intracaudal administration. Systemic administration of morphine, pentazocine and pethidine inhibited the CS. The inhibitory effects of opiates were antagonized by lysergide and methysergide but not by naloxone, chlorpromazine, dehydrobenzperidol, amphetamine and atropine. Contrary to their systemic administration, the investigated opiates morphine, pentazocine, pethidine and Met5-Enkephaline enhanced the CS, when injected into the caudate nucleus close to the site of stimulation. Those facilitating effects of opiates on the CS were completely blocked by naloxone. The results suggest that serotoninergic mechanisms might be involved in the action of opiates on the neuronal activity of the caudate nucleus.

Analgesic activity and opiate receptor affinity of new derivatives of N-butylpiperidine.

The three newly synthesized derivatives of N-butylpiperidine 1-butyl-4-phenyl-4-isonicotinoylaminoethylpiperidine (BG 25), 1-buty-isonicotinoylpiperidine (BG 26) and N-(1-butyl-4-phenyl-4-piperidinoyl) tetrahydropapaverine (BG 9) were evaluated for analgesic activity and opiate receptor affinity. All the three compounds showed analgesic activity both in hot-plate and flinch-squeak-jump test in mice, BG 9 being the most potent. The affinity of the compounds to opiate receptor was moderate (in comparison with pentazocine): the affinity of BG 9 was much greater than that of BG 25 and BG 26. The compounds showed a pronounced inhibitory action in stimulated guinea-pig ileum preparation; this was reversible by naloxone. As evaluated on pA basis, all three investigated compounds showed moderate antagonistic activity. Also in this respect BG 9 was more active than the other two compounds. Cholinolytic and strong spasmolytic properties were observed in isolated rat ileum preparation for BG 9 only.

Lack of habituation of pain evoked potentials after naloxone.

Pain evoked potentials (EPs) were recorded in nucleus caudatus (NC) of rabbits after electric stimulation of the dental pulp. After 50--60 noxious stimuli the decrease in amplitude of evoked potentials occured. Naloxone, 1 mg/kg, temporarily abolished this effect and even after 350 noxious stimuli the habituation was not observed. On the other hand, naloxone did not affect the diminution of monosynaptic transcallosal potentials (TC--EP) evoked by repeated stimulation. It may be suggested that the habituation of EPs elicited by pain stimulation is due to endorphin release.

Detection of antagonist activity for narcotic analgesics in mouse hot-plate test.

On the assumption that by the use of the hot-plate procedure the antagonist properties of narcotic analgesics could be detected, the effect of morphine, pentazocine, nalorphine and naloxone were investigated. The latency of paw-licking and jumping-off were determined and compared. The agonist, morphine, at doses of 0.025, 0.05 and 0.1 mmole/kg injected IP significantly increased paw-lick and jump-off latency above that seen in saline controls. The mixed agonist-antagonist, pentazocine, at doses of 0.048, 0.096 and 0.192 mmole/kg and nalorphine, an antagonist with some agonist activity, at doses of 0.032, 0.064 and 0.128 mmole/kg significantly increased the latency of paw-licking, but did not significantly change the jump-off latency. At a dose of 0.016 mmole/kg naloxone treated mice jumped from the hot-plate significantly sooner than controls but no effects of naloxone on paw-licking latency were observed. These results suggest that agonist properties are involved in the paw-lick response and that antagonistic properties determine jumping-off behavior.