The immunomodulatory effects of phlebotomy

The loss of blood by haemorrhage or routine phlebotomy as performed during
blood donation by healthy volunteers, has large effects on systemic iron
homeostasis. The relative shortage of erythrocytes after blood loss is
compensated for by increasing the production of new red cells by the bone
marrow. As iron is needed for effective haemoglobin synthesis, the transport of
iron to the bone marrow needs to be increased. This is accomplished by the
suppression of hepcidin production in the liver. Hepcidin is the central
regulator of iron homeostasis. It can regulate serum iron levels effectively by
downregulating iron channel ferroportin on iron exporting cells. Hepcidin
production is increased in response to inflammation en high systemic iron
content, and is suppressed by increased erythrocyte production, hypoxia,
anemia, and low systemic iron content. Therefore, blood loss leads to hepcidin
suppression, increased release of iron into the circulation and decrease of
iron stores.
Alterations in iron metabolism can have immunomodulatory effects. The intra
cellular iron content in macropahges and monocytes, has shown pro-inflammatory
effects in several investigations. Hepcidin is reported to have
pro-inflammatory effects in some reports, and anti-inflammatory effects in
others.
Although phlebotomy is routinely performed in blood donors, and seemingly does
not have significant health risks, it is highly relevant to know what the
effect of phlebotomy is on immunity. Alterations in immunity due to phlebotomy
could have beneficial effects, like the suppression of the low grade
inflammatory process that contributes to atherosclerosis, but in theory could
also contribute to a suppressed innate immune response that could increase the
risk of infection. This is not only relevant for blood donors, but also for
patients suffering from blood loss and for daily clinical practice in which
blood is routinely drawn of patients for laboratory determinations.

To assess the ex vivo cytokine production of whole blood during 28 days after
phlebotomy (routine withdrawal of 500 ml of blood).

Prospective intervention study in 10 healthy male volunteers.

10 healthy volunteers will donate 500 mL at the blood bank, according to normal
procedures (day 0).


On day -1, 0, 1, 3, 5, 7, 14, 21 and 28 blood will be drawn for the
determination of:
- ex vivo cytokine production (TNF-alfa, IL-6, IL-10).
- hemoglobin, hematocrit and leucocyte differentiation.
- hepcidin.
- Iron parameters (serum iron, transferrin saturation, ferritin).

Phlebotomy (withdrawal of 500 mL volbloed)

The study consists of 11 visits:
- 1 screening visit
- 1 phlebotomy visit
- 9 follow-up visits

At the screening, a questionaire will be filled out by the subject, and a short
physical examination will be performed.

At the visit for phlebotomy at the blood bank, another questionaire will be
filled out for registration purposes at the blood bank. Also, the hemoglobin
level will be checked. Then, a vene in the elbow will be puntured and 500 mL of
blood will be withdrawn.

At the follow-up visits, each time 2 tube of blood will be drawn (7 mL total).
Also, subjects will be questioned for the occurence of adverse events,
especially regarding intercurrent infections.