Modulation of adhesion molecule profiles on alveolar macrophages and blood leukocytes.
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 beta(2) 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 beta(2) 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 beta(2) 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.


CONCLUSIONS
Developmental origin, degree of cell differentiation (maturity) as well as different environmental conditions all heavily influence the expression and modulation pattern of beta(2) integrins and L-selectin on leukocytes and Mo-derived AM.
Haugen
T S
TS
Research Forum, Ullevaal University Hospital, Oslo, Norway. torbjhau@online.no
Skjonsberg
O H
OH
Nakstad
B
B
Lyberg
T
T
D000328:Adult; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D001999:Bronchoscopy / Q000379:methods; D002478:Cells, Cultured; D005260:Female; D005336:Fiber Optic Technology; D005434:Flow Cytometry; D006801:Humans; D016023:Integrins / Q000032:analysis*; D007962:Leukocytes / Q000737:chemistry*; D008168:Lung / Q000166:cytology; D016676:Macrophages, Alveolar / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012680:Sensitivity and Specificity
D016023:Integrins