Airway generation-specific differences in the spatial distribution of immune cells and cytokines in allergen-challenged rhesus monkeys.

BACKGROUND: Accumulation of immune cell populations and their cytokine products within tracheobronchial airways contributes to the pathogenesis of allergic asthma. It has been postulated that peripheral regions of the lung play a more significant role than proximal airways with regard to inflammatory events and airflow obstruction. OBJECTIVE: To determine whether immune cell populations and associated cytokines are uniformly distributed throughout the conducting airway tree in a non-human primate model of allergic asthma. METHODS: We used a stereologic approach with a stratified sampling scheme to measure the volume density of immune cells within the epithelium and interstitium of trachea and 4-5 intrapulmonary airway generations from house dust mite (HDM) (Dermatophagoides farinae)-challenged adult monkeys. In conjunction with immune cell distribution profiles, mRNA levels for 21 cytokines/chemokines and three chemokine receptors were evaluated at four different airway generations from microdissected lungs. RESULTS: In HDM-challenged monkeys, the volume of CD1a+ dendritic cells, CD4+ T helper lymphocytes, CD25+ cells, IgE+ cells, eosinophils, and proliferating cells were significantly increased within airways. All five immune cell types accumulated within airways in unique patterns of distribution, suggesting compartmentalized responses with regard to trafficking. Although cytokine mRNA levels were elevated throughout the conducting airway tree of HDM-challenged animals, the distal airways (terminal and respiratory bronchioles) exhibited the most pronounced up-regulation. CONCLUSION: These findings demonstrate that key effector immune cell populations and cytokines associated with asthma differentially accumulate within distinct regions and compartments of tracheobronchial airways from allergen-challenged primates.

Selective contact during TCR recognition.

Recent structural analysis of the peptide-MHC complex reveals that an antigenic peptide binds to MHC in only one conformation and that side chains anchoring in the binding pocket would not contact TCR. The identification of all the MHC-anchoring residues on an antigenic peptide is a prerequisite to understand how a given peptide interacts with the TCR. In a combination of binding analysis and model simulation, model peptide lambda repressor cl 16-26 was shown to bind to I-Ek through four anchor residues (Leu18, IIe21, Glu23 and Lys26), a pattern found in many I-Ek-binding peptides. TCR reactivity analysis clearly indicates a great variation in the interaction with cl 16-26 by T cells generated from different strains of I-Ek-bearing mice. Most of the T cell generated from A/J mice reacted with the central regions of cl 16-26, while there is a great diversity on the recognition of cl 16-26 by T cells from C3H and B10.BR mice. Despite the diverse interactions with antigenic peptide by these T cells, most TCR-E-k contacts are limited to the central region of the I-Ek beta-chain. T cells recognizing only the N-terminal part of cl 16-26 were found to contact I-Ek at nearly the same residues as T cells interacting with the C-terminal of cl 16-26. TCR-I-Ek recognition was apparently independent of TCR-cl 16-26 contact. The discordant TCR-peptide and TCR-MHC interaction may represent a unique feature of TCR recognition.

Flexibility of the T cell receptor repertoire.

Alternative T cell receptor (TcR) gene usage between mice of different Mls alleles has been demonstrated in a number of T cell responses. A clear illustration of a flexible TcR V beta usage in the same strain of mice remains to be established. Using a model system in which I-Ek-restricted T cells recognizing lambda repressor cI protein (cI) 12-26 and pigeon cytochrome c (pcc) 81-104 predominantly use V beta 3 in B10.A and B10.BR mice, and V beta 1 in Mls-2a-bearing A/J and C3H mice, we have first demonstrated that the hierarchy of TcR V beta usage can not be inferred from one strain of mice to the other. The presumed flexibility of V beta 3 to V beta 1 did not exist in B10.BR mice in the given responses. Instead, a switch of dominant TcR from V beta 1/V beta 3 to V beta 8 was identified in C3H and B10.BR mice. In contrast, there was an absolute rigidity in TcR repertoire usage in some mouse strains such as A/J. The lack of flexibility was not due to slow generating kinetics of replacing T cells; since A/J mice treated with staphylococcal enterotoxin A from birth on still responded poorly to cI 12-26 and pcc 81-104. Therefore, whether TcR V beta usage in a T cell response would be flexible or rigid is highly dependent on each strain of mice. However, even the plasticity seen in B10.BR mice is very limited and further tolerance of the V beta 8+ population results in non-responsiveness toward the given antigens.

Effect of free fatty acids on liposome susceptibility to imidazole antifungals.

The presence of free fatty acids in liposome model membranes sensitizes these membranes to the action of the imidazole antifungals, clotrimazole, micronazole, and sulconazole. Unsaturation of the fatty acids is an important variable; the effect of linoleic and oleic acids is much greater than that of stearic acid. The imidazoles differ somewhat in action, with clotrimazole potency greatest both on membranes with and without fatty acids. Sulconazole has very little activity on membranes without fatty acids even at the highest concentrations tested. The data are discussed with reference to the susceptibility of various cells to the imidazoles and the specificity of imidazole action. A modification of the enzymatic method generally used for assay of marker glucose with liposome systems is also presented.

Induction of colitis in hamsters by topical application of antibiotics.

Syrian hamsters are exquisitely sensitive to clindamycin; as little as 1 mg/kg of clindamycin given systemically causes a fatal colitis. Clindamycin and erythromycin were applied topically daily to the shaved backs of Syrian hamsters in a hydroalcoholic vehicle. A daily dose of 0.1 mg of clindamycin was lethal to more than half the hamsters and 1 mg to all the animals. The antibiotic-associated toxin from Clostridium difficile was present in their cecal material. Based on body surface areas and estimated usual volumes applied, the lethal dose in hamsters is not dissimilar to that given humans for acne. Oral tetracycline therapy protected the animals from clindamycin toxicity, but the animals died three days after stopping tetracycline if topical clindamycin applications were continued.

Dissociation between ion permeability and the lethal action of polyene antibiotics on Candida albicans.

Kinetic data on potassium release from and killing of Candida albicans by the four polyene antibiotics amphotericin B, amphotericin B methyl ester hydrochloride, nystatin, and nystatin methyl ester hydrochloride are presented. The nystatins were relatively more effective than the amphotericins in causing potassium release rather than killing. These data suggest that the aqueous channels or pores formed by the polyene antibiotics are not central to the lethal action of the drugs.