Activation of platelets in bronchial asthma.
OBJECTIVE
To investigate whether platelets are activated in asthmatics with increased release of preformed mediators and to investigate the influence of oral administration of theophylline on them.


METHODS
Comparison of the intracellular free calcium concentration ([Ca2+]i) in platelets as an indicator of platelet activation, CD62P expression on platelets, and the chemokine regulated upon activation in normal T cells expressed and presumably secreted (RANTES) level in platelet-rich buffer supernatants between asthmatics and normal subjects.


METHODS
The respiratory outpatient clinics, Hiroshima University, Japan.


METHODS
Twenty-five normal volunteers, 19 asthmatics taking no oral drugs associated with asthma treatment (group A), and 18 asthmatics taking oral theophylline (group B).


RESULTS
While the resting [Ca2+]is in platelets were similar among the three groups, the [Ca2+]is in group A were significantly higher than those in normal subjects (p<0.05) and group B (p<0.01) after thrombin or 9,11-epithia-11,12-methano-thromboxane A2 (STA2) stimulation in the absence of external Ca2+. The CD62P expression level and RANTES level in group A after STA2 stimulation were significantly higher than those in normal subjects and group B (p<0.05).


CONCLUSIONS
We conclude that agonist-mediated activation of platelets is augmented in asthmatics resulting in enhanced release of chemokine such as RANTES, which could be suppressed by oral administration of theophylline.
Moritani
C
C
Second Department of Internal Medicine, Hiroshima University School of Medicine, Japan.
Ishioka
S
S
Haruta
Y
Y
Kambe
M
M
Yamakido
M
M
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001249:Asthma / Q000097:blood* / Q000188:drug therapy; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use; D002118:Calcium / Q000032:analysis; D016022:Case-Control Studies; D018946:Chemokine CCL5 / Q000032:analysis; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000032:analysis / Q000235:genetics; D010972:Platelet Activating Factor / Q000494:pharmacology; D015539:Platelet Activation / Q000187:drug effects; D013806:Theophylline / Q000008:administration & dosage / Q000627:therapeutic use; D013917:Thrombin / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology
D001993:Bronchodilator Agents; D018946:Chemokine CCL5; D019007:P-Selectin; D010972:Platelet Activating Factor; D013928:Thromboxane A2; C037866:STA 2; D013806:Theophylline; D013917:Thrombin; D002118:Calcium