Smoking and elevated leukocyte counts are risk factors for cardiovascu
lar disease, Experimental studies suggest that leukocyte activation ma
y be a requirement for certain cardiovascular complications, Clinical
studies have demonstrated activated leukocytes in the peripheral blood
of stroke victims, Accordingly, neutrophil activation in unseparated
whole blood of smokers as well as naive neutrophils of non-smokers exp
osed to plasma of smokers was investigated, Both spontaneous superoxid
e formation as determined by nitroblue tetrazolium reduction, as well
as pseudopod formation, are significantly elevated in autologous: neut
rophils of smokers, The surface expression of CD18 and L-selectin on a
utologous circulating neutrophils of smokers is not significantly diff
erent from non-smoker controls, In contrast, incubation of naive neutr
ophils with smoker plasma leads to significantly higher levels of supe
roxide formation, pseudopod formation, and L-selectin shedding compare
d with non-smoker plasma, suggesting that the plasma of smokers contai
ns a transferable factor which causes leukocyte activation, The result
s indicate that analysis of blood samples from large peripheral veins
may not accurately reflect leukocyte activation in the circulation sin
ce activated leukocytes have a higher probability to be trapped in the
microcirculation.