Modulation of Adhesion Molecule Profiles on Alveolar Macrophages and Blood Leukocytes

Abstract

Background: Cell adhesion molecules are believed to be essential for blood cell recruitment to the lung and for the movement of alveolar macrophages (AM) within the lung. Objective: To investigate the expression pattern of L-selectin and β₂ integrins on blood leukocytes and AM, including AM of various maturity. Methods: Flow cytometry was used to study the expression of L-selectin (CD62L) and of the β₂ integrins CD11a, CD11b, and CD11c on AM (including density-defined subpopulations), monocytes (Mo), polymorphonuclear neutrophils (PMN) and lymphocytes (Ly) sampled from healthy individuals, during incubation with and without lipopolysaccharide (LPS). Results: A significantly different modulation pattern of β₂ integrins and L-selectin was demonstrated on Mo and AM, cells of the same differentiation lineage. In contrast to AM, Mo had a marked ability to respond to LPS stimulation by increased expression of CD11a, CD11b and CD11c and decreased expression of L- selectin. These molecules were expressed to a similar degree on AM, whereas the basal levels of CD11b and L-selectin were considerably higher on Mo than on AM. A significantly different expression of CD11a as well as differences in the regulation of L-selectin during incubation were also demonstrated between density-defined subpopulations of AM. CD11a could not be upregulated on PMN, otherwise the modulation patterns of CD11b, CD11c and L-selectin were similar to that on Mo. The expression of CD11a on Ly was 3- to 6-fold higher than on Mo, PMN and AM. The level of CD11b decreased significantly upon incubation (uninfluenced by LPS stimulation), and CD11c was hardly expressed on Ly. The level of L-selectin on Ly was higher than on Mo, AM and PMN and was not decreased during incubation. Conclusion: Developmental origin, degree of cell differentiation (maturity) as well as different environmental conditions all heavily influence the expression and modulation pattern of β₂ integrins and L-selectin on leukocytes and Mo-derived AM.

Airway Inflammation and Upregulation of β2 Mac‐1 Integrin Expression on Circulating Leukocytes of Female Ragpickers in India

“…Overexpression of CD11b/CD18 on leukocyte surfaces in ragpickers, therefore, possibly underscores stimulation of immune defense to combat pathogenic microorganisms in their working environment 16) . This is consistent with a report showing higher expression of CD11b on neutrophil and monocyte surfaces during challenge from bacterial pathogens 20) . Sustained overexpression of β 2 Mac-1 integrin, however, could be harmful because it prolongs inflammation by delaying neutrophil apoptosis causing tissue damage 6) .…”

Glycodelin-A Stimulates Interleukin-6 Secretion by Human Monocytes and Macrophages through L-selectin and the Extracellular Signal-regulated Kinase Pathway

“…S5), consistent with previous studies (23,24). The inclusion of anti-L-selectin antibody significantly (p Ͻ 0.05) reduced the binding of fluorescently labeled GdA to monocytes (Fig.…”

Protein tyrosine kinase and p38 MAP kinase pathways are involved in stimulation of matrix metalloproteinase-9 by TNF-α in human monocytes

“…In this study, we report that cells developed from cultured monocytes displayed the phenotype of tissue macrophages with the phenotype CD14 low CD11b low CD64 low HLA-DR + [24][25][26][27], and SB203580 and tyrphostin 25 did not alter the maturation process of monocytes. We recently showed that the inflammatory cytokines IFN-␥ and TGF-␤1, which accelerated differentiation of monocytes, down-regulated MMP-9 synthesis and release in differentiating cells [28].…”

“…2). Indomethacin 25 29 ± 6 (2-13) 27 ± 9 (7-59) 48 ± 3 * (21-290) 12 ± 6 (46-90) +Both 28 ± 5 (14-17) 36 ± 11 67 SB202474 (5 M), an inactive analog of SB203580 for p38 MAPK inhibition study [30] was without effect (<10%, data not shown). When added together, tyrphostin 25 and SB203580 inhibited MMP-9 production (Fig.…”

“…The phenotype of monocytes and developed macrophages is depicted in Table 1. Day-7 macrophages displayed the phenotype CD11b low CD14 low CD64 low HLA-DR + consistent with the phenotype of tissue macrophages [24][25][26][27]. Total RNA from cultured monocytes was isolated, reverse-transcribed and subjected to PCR amplification.…”