Related Experiment Videos
Cell-free granulocyte colony inhibiting activity derived from human polymorphonuclear neutrophils
Abstract:
Human PMN (non-adherent: density greater than 1.070 g/cm3) were used to prepare cell-free colony inhibiting activity (CIA). Intact PMN, PMN conditioned media (serum-free or serum-containing) and supernatant from immediately lysed PMN equally reduced the numbers of spontaneous bone marrow (density less than 1.070 g/cm3; depleted of PMN) colonies and clusters. Addition of CIA reproducibly reduced colony and/or cluster numbers by 35-70%. CIA was heat labile being inactivated at 37 degrees C. Daily additions of CIA reduced colony numbers even further; inhibition was dependent on [PMN] used to prepare CIA and on the potency of stimulation produced by colony stimulating cells (CSC). PMN from some patients with leukemia were inactive as inhibitors and did not condition media with CIA. All experiments were thereafter controlled by parallel assessment of supernatant of lysed PMN not demonstrating any CIA. CIA appears to be not only stored in PMN but released from viable, as well as degranulating PMN. Although not species-specific, CIA was specific in its nontoxic action on CSC; colony forming cells and cell-free colony stimulating activity were not affected. The influence of CIA on CSC could be reversed within 10 minutes, but not within 35 minutes of incubation. CIA may have possible physiological relevance.
Insights
Cell-free colony inhibiting activity (CIA) from human neutrophils reduces bone marrow colony formation. This heat-labile activity, released from viable or lysed neutrophils, specifically inhibits colony stimulating cells.
Area of Science:
- Hematology
- Cell Biology
Background:
- Neutrophils (PMN) are key immune cells involved in various physiological processes.
- Colony inhibiting activity (CIA) has been observed in neutrophils, but its precise nature and function require further elucidation.
Purpose of the Study:
- To characterize the cell-free colony inhibiting activity (CIA) derived from human neutrophils.
- To investigate the source, stability, specificity, and potential physiological relevance of neutrophil-derived CIA.
Main Methods:
- Preparation of cell-free CIA from human neutrophils (density > 1.070 g/cm3).
- Assay of CIA's effect on spontaneous bone marrow colony and cluster formation (density < 1.070 g/cm3).
- Evaluation of CIA's heat lability, dose-dependency, and specificity towards colony stimulating cells (CSC).
Main Results:
- Cell-free CIA from intact, lysed, or conditioned neutrophils significantly reduced bone marrow colony and cluster numbers (35-70% inhibition).
- CIA was heat-labile, inactivated at 37°C, and its inhibitory effect was dependent on neutrophil concentration and CSC stimulation potency.
- CIA specifically inhibited CSC without affecting colony-forming cells or colony-stimulating activity, with reversible effects observed within 10 minutes.
Conclusions:
- Neutrophils store and release cell-free CIA, which can be obtained from viable or lysed cells.
- CIA exhibits specific, non-toxic inhibitory action on CSC, suggesting a potential physiological role in regulating hematopoiesis.