The aim of this study was to describe the kinetics of the cytokine release and the expression of activation markers on lymphocytes after stimulation of peripheral blood mononuclear cells (PBMC) with whole killed Streptococcus pneumoniae. The cytokine release and the expression of CD25 and HLA-DR on T cells, and CD69 on T cells, B cells and NK cells, were measured at different times. Our results show that tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-10 and IL-12 reached maximal levels at 24 h, while IL-6, IL-8, TNF-beta and interferon (IFN)-gamma increased throughout the 1-week test period. The strains tested gave an increased expression of CD69 on all cell types, as well as an increase of CD25 and HLA-DR expression on T cells. The maximal CD69 expression was seen after 24 h on T cells and NK cells, while the B-cell expression of CD69 reached a plateau at the same time. All the cells still expressed CD69 on their surfaces after 1 week. In conclusion the results indicate that there was probably an early activation of monocytes leading to a polyclonal activation of lymphocytes.

In this study we investigated if smoking subjects with a normal or slightly decreased lung function differ in the lymphocyte pattern compared to never-smokers. In a group of 'healthy' smokers (n = 58) and never-smokers (n = 34) 60 years old, we investigated the lymphocyte pattern in both BAL (n = 30 and n = 18 respectively), bronchial epithelium and lamina propria (n = 14 and n = 10 respectively) and blood. We found that all subjects, despite smoking history, had a higher number of CD8+ cells per mm2 in the epithelium compared to the lamina propria in the bronchial biopsies. In smokers, these CD8+ cells were significantly negatively correlated to FEV1 (r = -0.56, P = 0.04). In smokers, the number of CD8+ lymphocytes was higher and the T cell activation markers (CD57+ and CD28+) were lower in BAL, than in never-smokers. This last finding was also seen in blood for CD3+ 57+. We conclude, that in 'healthy' smokers the lymphocyte patterns are different compared to never-smokers, to some extent in BAL. There is also a relation between lymphocytes in the bronchial mucosa and lung function. This has previously been shown in patients with chronic obstructive pulmonary disease (COPD) and chronic bronchitis but not in asymptomatic smokers.

In this study healthy never-smoking subjects (n = 18) were recruited from a population study. Bronchoalveolar lavage (BAL), blood lymphocytes and bronchial biopsies, analysed both in the epithelium and lamina propria, were stained for T and B lymphocytes, natural killer (NK) cells and different subpopulations of T lymphocytes. In BAL, significantly higher proportions of T lymphocytes (CD3), T lymphocyte activation markers; HLA-DR, CD26+, CD49a+, CD54+ and CD69+, helper T (CD3+4+) and memory helper T lymphocytes (CD4+45RO+29+) and memory T lymphocytes (CD3+45RO+) were found, compared to blood. However, the proportion of IL-2 receptor-positive T lymphocytes (CD25+) was lower in BAL than in blood. A previously described higher ratio of CD3+4+/CD3+8+ in BAL than in blood (3.4 vs 1.7; P = 0.001) was confirmed. In bronchial biopsies, we found significantly higher numbers of CD8+ cell profiles per mm2 in the epithelial compared to the lamina propria compartment. We conclude that healthy never-smoking men have higher levels of activated memory T lymphocytes in BAL than in blood, and that the T-cell subpopulations differ in the epithelial compared to the lamina propria compartment in the bronchial mucosa and these compartments should be analysed separately. It is reasonable to think that there is a gradient from blood to the airway lumen where T cells are recruited from blood to take part in the defense towards damaging agents.

Polymorphonuclear granulocytes, which provide a major defence against Streptococcus pneumoniae infections, are attracted to and activated by various cytokines. The aim of this study was to analyse the cytokine response of human peripheral blood mononuclear cells to stimulation with S. pneumoniae. Strains belonging to serogroups 4, 6, 14, 19 or 23, were isolated from nasopharynx, middle ear fluid, cerebrospinal fluid or blood. All strains induced a marked proliferative response of the peripheral blood mononuclear cells; the stimulatory index was 34+/-11. High levels of pro-inflammatory cytokines were induced, i.e. interleukin (IL)-1beta (53+/-25 ng/ml), IL-6 (347+/-41 ng/ml) and tumour necrosis factor (TNF)-alpha (15+/-4 ng/ml). Also, chemokines and immunoregulatory cytokines including IL-8 (215+/-224 ng/ml), IL-10 (122+/-60 pg/ml), IL-12 (1195+/-648 pg/ml), interferon (IFN)-gamma (18+/-4 ng/ml) and granulocyte macrophage colony-stimulating factor (135+/-80 pg/ml) were induced. Several of these cytokines can up-regulate phagocytosis and the killing of bacteria. Interestingly, strains isolated from middle ear fluid and blood elicited significantly fewer IL-8 and significantly more IL-12 and IL-10 than strains from nasopharynx. They also induced a stronger proliferative response. Our results indicate that pneumococci are potent inducers of cytokines, especially IL-12, favouring T-helper cell type 1 (Th1) responses.

The aim of this study was to analyse the in vitro response of human peripheral blood mononuclear cells to stimulation with killed Haemophilus influenzae strains of different capsular types, isolation sites and from cases with different forms of infections. The mean stimulatory index using 10(6) bacteria/well was 10, and 80 when 10(8) bacteria/well were used for stimulation. The mean+/-SD level was 13+/-4 ng/ml for interleukin (IL)-1beta, 128+/-73 ng/ml for IL-6, 203+/-122 ng/ml for IL-8, 3160+/-1220 pg/ml for IL-10, 29+/-40 pg/ml for IL-12, 2800+/-1790 pg/ml for tumour necrosis factor (TNF)-alpha and 4+/-7 ng/ml for interferon (IFN)-gamma, when stimulating cells with the lower dose of 10(6) bacteria/well. Using the higher bacterial dose, the levels of IL-1beta, TNF-alpha and IL-12 remained similar, whereas the IL-6, IL-8 and IL-10 levels were significantly lower, and IFN-gamma levels were significantly higher. Strains isolated from the bronchial tree induced significantly higher levels of IFN-gamma and significantly lower levels of IL-6, IL-8 and IL-10 than strains from other isolation sites. In conclusion, H. influenzae generated phagocyte-activating cytokines and an IL-10/IL-12 ratio that was 1090 times that described previously for Streptococcus pneumoniae.

This study describes the antibody response to two bacterial antigens, pneumolysin toxoid (PL) and purified pneumococcal capsular polysaccharide (PPS) 19F, in bronchoalveolar lavage (BAL) and in serum in rats after aerosol immunization with whole killed Streptococcus pneumoniae. To study the importance of bacterial adherence for antibody formation, one well-adhering and one poorly adhering strain of S. pneumoniae was used. The results show local specific anti-PPS 19F IgA, IgM and IgG antibody activities after aerosol immunization. Anti-PL antibody activity in all three immunoglobulin classes was found, although the anti-PL activity was lower than the anti-PPS 19F antibody activity. The IgA anti-PPS 19F antibody activity in BAL after immunization with the well-adhering strain was higher than with the poorly adhering strain. We conclude that aerosol immunization with S. pneumoniae induces a local, specific antibody production in the lung of the rat.