Studies on the presence and possible oscillations of granulocytic progenitor cells (CFU-C) in human blood

Area of Science:

• Hematology
• Cell Biology
• Immunology

Background:

• Colony-forming unit cells (CFU-C) are crucial for hematopoiesis.
• Understanding CFU-C dynamics in peripheral blood is important for monitoring hematopoietic activity.
• Previous studies have not extensively characterized the temporal oscillations of CFU-C in healthy individuals.

Purpose of the Study:

• To investigate the presence and potential oscillations of CFU-C in the peripheral blood of healthy volunteers over a 70-day period.
• To compare CFU-C levels and oscillation patterns when using different sources of colony-stimulating activity (CSA).

Main Methods:

• Peripheral blood samples were collected 3 times weekly from 3 healthy volunteers over 70 days.
• Mononuclear cells (MNC) were isolated using dextran sedimentation and iron ingestion.
• Cryopreserved MNC were cultured in soft agar with either a leucocyte feeder layer or human placental conditioned medium as CSA.
• CFU-C counts were determined per ml of blood.

Main Results:

• CFU-C counts varied significantly depending on the CSA source.
• Cultures with a leucocyte feeder layer showed average CFU-C counts of 29, 43, and 118 per ml, with no systematic oscillations.
• Cultures with human placental conditioned medium exhibited average CFU-C counts of 255, 125, and 222 per ml.
• Significant oscillations with periods of 23, 19, and 25 days were observed when using placental conditioned medium.

Conclusions:

• The source of colony-stimulating activity significantly influences the detection of CFU-C oscillations in peripheral blood.
• Human placental conditioned medium revealed significant, regular oscillations in CFU-C levels in healthy volunteers.
• These findings suggest a potential endogenous rhythmicity in hematopoietic progenitor cells that may be masked by certain culture conditions.