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Repeated challenge with antigen is involved in the pathogenesis of a variety of pulmonary diseases. Patients with cystic fibrosis (CF) experience recurrent pulmonary colonization with Pseudomonas aeruginosa before establishment of chronic lung infection. To mimic recurrent lung infections in CF patients, the lungs of susceptible BALB/c mice were re-infected with P. aeruginosa 14 days after the initial infection. Singly-infected BALB/c mice, as well as non-infected mice, were used as controls. Decreased mortality and milder lung inflammation in re-infected BALB/c mice, as well as a tendency for improved clearance of bacteria, was observed when compared with singly-infected mice. The improved outcome in re-infected mice correlated with changes in CD4 cell numbers. Surface expression of LFA-1 on pulmonary CD4 cells was increased in re-infected compared with singly-infected mice. Moreover, resistance to re-infection was paralleled by a shift towards a Th1-dominated response and increased IL-12 production. No significant increase in serum IgG was observed in the re-infected mice. In conclusion, these results indicate a protective role for a Th1-dominated response, independent of antibody production, in chronic P. aeruginosa lung infection in CF.

Peripheral blood mononuclear cells (PBMC) from patients who have recovered from visceral leishmaniasis often respond to Leishmania antigens in vitro by production of both IL-4, IFN-gamma and IL-10. In order to establish the cellular sources of these cytokines, we activated cells from individuals with a history of visceral leishmaniasis with Leishmania antigen for 6 days in culture, and identified cytokine production at the single-cell level by flow cytometry. The cytokines were only found in CD3+ cells and among these mainly within the CD4+ subset. The percentage of cytokine-producing cells was compared in Leishmania-activated PBMC cultures from the previous patients and from individuals living in a village where leishmaniasis does not occur. The percentage of IL-10- and IFN-gamma-containing cells was significantly higher in the previous patients than in the controls, indicating that Leishmania-specific T cells producing IL-10 and/or IFN-gamma had been expanded as a result of the infection. The cytokine-producing cells in the previous patients could be divided into three types: (i) cells producing IFN-gamma only; (ii) cells producing IL-4 only; and (iii) cells producing IFN-gamma and IL-10 simultaneously. The first and second group of cells can be described as Th1- and Th2-type cells, respectively. The third group could be a regulatory subset of T cells important for maintaining a balance between Th1- and Th2-type cells in these individuals.

In sputa of 21 cystic fibrosis patients suffering from chronic Pseudomonas aeruginosa lung infections, activities of lysosomal proteases released from polymorphonuclear leukocytes (PMN) and immune complexes were quantitatively determined. The results showed that low immune complex values correlated with high protease activities and vice versa. In a longitudinal study fluctuating, reciprocal changes of the parameters were observed. Therefore, the hypothesis was investigated as to whether PMN elastase cleaves immune complexes and regulates inflammation. It was shown that treatment of immune complex-positive sputa with PMN elastase decreased IgG and IgA immune complex values and lead to cleavage of the immunoglobulins in the hinge region. PMN elastase-treated samples were not able to stimulate the oxidative burst of PMN. Cleavage of in vitro built immune complexes did not lead to liberation of bound antigen. Western blot analysis of one sputum sample revealed split products of the IgG heavy chain. The results suggest that PMN elastase splits off the Fc portion of immunoglobulins in immune complexes and thus regulates inflammation by a feedback mechanism leading to cyclic inflammatory states.

The effect of normal human peripheral blood polymorphonuclear leucocytes on in vitro multiplication of Plasmodium falciparum malaria parasites was investigated. It was shown that normal neutrophils were able to phagocytose parasitized erythrocytes and free parasites and thus inhibit in vitro multiplication of the parasite. Stimulation of the neutrophils by phorbol myristate acetate, a potent stimulus of leucocyte oxidative metabolism, resulted in enhanced inhibition of parasite growth. Superoxide dismutase, scavenger of superoxide anion, catalase, inhibitor of hydrogen peroxide, and sodium azide, inhibitor of myeloperoxidase, did not abrogate the inhibitory ability of the neutrophils. The results indicate that polymorphonuclear leucocytes play an important role in the defence against P. falciparum malaria.

Twenty-seven intestinal lymphoma patients were studied. Abnormal alpha-chain immunoglobulin was detected in the sera of seven of these patients. The alpha-chain disease patients were from the rural areas of Southern Iran. They were of low socio-economic status and their age ranged from 15-44 years. Predominant clinical features were malabsorption, diarrhoea , abdominal pain, vomiting, and weight loss. Infiltration of mucosa of the small intestine with plasma cells and also distortion and flattening of the villi were common histopathologic characteristics of these patients. Involvement of mesenteric lymph nodes with infiltration of tumour cells was observed in a number of cases. Protein studies revealed no significant differences between the serum immunoglobulin levels of these patients and normal values. Immunoelectrophoresis using monospecific antiserum against H-chain of human IgA demonstrated the abnormal precipitin band of alpha-chain disease protein.