The Effect of Glucocorticoids on the Expression of L-Selectin on Polymorphonuclear Leukocyte

A novel method to quantify the turnover and release of monocytes from the bone marrow using the thymidine analog 5'-bromo-2'-deoxyuridine

The present study was designed to develop methods to study the production and release of monocytes from the bone marrow using the thymidine analog 5'-bromo-2'-deoxyuridine (BrdU). Dividing monocytes in bone marrow were labeled with BrdU (MOBrdU), and their release into the blood and disappearance from the circulation were monitored using a double immunostaining method. The first MOBrdU appeared in the circulation 4 h after labeling with BrdU and peaked at 18 h when 34.3 +/- 5.8% of monocytes were labeled. The calculated transit time of monocytes through bone marrow was 38.1 +/- 3.1 h in control rabbits with a half-life (T1/2) of 12.7 h. Instillation of Streptococcus pneumoniae into the lung accelerated the release of monocytes from bone marrow (peak at 10 h) and shortened their bone marrow transit time (27.1 +/- 1.8 vs. 22.6 +/- 0.6, vehicle vs. pneumonia; P < 0.05). We conclude that this nonradioisotope method provides a novel way to monitor monocyte kinetics and confirmed previous reports that a focal pneumonia shortens monocyte marrow transit and increases their release into the circulation.

Immunologic and hemodynamic effects of "low-dose" hydrocortisone in septic shock: a double-blind, randomized, placebo-controlled, crossover study

Within the last few years, increasing evidence of relative adrenal insufficiency in septic shock evoked a reassessment of hydrocortisone therapy. To evaluate the effects of hydrocortisone on the balance between proinflammatory and antiinflammation, 40 patients with septic shock were randomized in a double-blind crossover study to receive either the first 100 mg of hydrocortisone as a loading dose and 10 mg per hour until Day 3 (n = 20) or placebo (n = 20), followed by the opposite medication until Day 6. Hydrocortisone infusion induced an increase of mean arterial pressure, systemic vascular resistance, and a decline of heart rate, cardiac index, and norepinephrine requirement. A reduction of plasma nitrite/nitrate indicated inhibition of nitric oxide formation and correlated with a reduction of vasopressor support. The inflammatory response (interleukin-6 and interleukin-8), endothelial (soluble E-selectin) and neutrophil activation (expression of CD11b, CD64), and antiinflammatory response (soluble tumor necrosis factor receptors I and II and interleukin-10) were attenuated. In peripheral blood monocytes, human leukocyte antigen-DR expression was only slightly depressed, whereas in vitro phagocytosis and the monocyte-activating cytokine interleukin-12 increased. Hydrocortisone withdrawal induced hemodynamic and immunologic rebound effects. In conclusion, hydrocortisone therapy restored hemodynamic stability and differentially modulated the immunologic response to stress in a way of antiinflammation rather than immunosuppression.