Related Experiment Video
Updated: Apr 5, 2026
Determining Immune System Suppression versus CNS Protection for Pharmacological Interventions in Autoimmune Demyelination
Published on: September 12, 2016
Comparative analysis of pathologic processes developing in mice housed in SPF vs non-SPF conditions and treated with
Evgeniya V Dolgova1, Yaroslav R Efremov1, Oleg S Taranov2
1Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia.
Abstract:
In our earlier studies, we observed that when mice are treated with cyclophosphamide and fragmented exogenous dsDNA (18-30 h post cytostatic treatment), they develop a very characteristic set of symptoms and 80-90% of such animals succumb within 6-25 days. This was called "delayed death" phenomenon, and the gap between cyclophosphamide and DNA injections required for such phenotype to develop was termed "death window". We established that mice succumbed to multi-organ failure, which was caused by systemic inflammation and sepsis. These processes unfolded along with accidental involution of lymphoid organs, which resulted from the failure of CD34(+) hematopoietic stem cells to differentiate into lymphoid lineage progenitors. Here we compare SPF and non-SPF animals, and demonstrate that the major cause of systemic inflammation and sepsis observed upon such treatments is activation of an opportunistic infection. Mice of the same strain (CBA) housed under SPF conditions do not develop the characteristic symptoms, nor do they become moribund. Yet, regardless of the breeding conditions, upon synergistic action of cyclophosphamide and dsDNA, CD34(+) hematopoietic stem cells consistently fail to give rise to lymphoid lineage progenitors. We demonstrate that this differentiation defect is reversible and that population of lymphoid progenitors is restored by day 29 after cyclophosphamide injection.
Insights
Mice treated with cyclophosphamide and dsDNA experience delayed death due to opportunistic infections. This immune defect, affecting hematopoietic stem cells, is reversible and linked to breeding conditions.
Area of Science:
- Immunology
- Hematology
- Microbiology
Background:
- Cyclophosphamide and exogenous dsDNA treatment in mice induces a "delayed death" phenomenon.
- This phenomenon is characterized by multi-organ failure, systemic inflammation, and sepsis.
- A critical factor is the failure of CD34(+) hematopoietic stem cells to differentiate into lymphoid progenitors.
Purpose of the Study:
- To investigate the role of breeding conditions (SPF vs. non-SPF) in the "delayed death" phenomenon.
- To identify the primary cause of systemic inflammation and sepsis in treated mice.
- To assess the reversibility of the hematopoietic stem cell differentiation defect.
Main Methods:
- Comparison of CBA mice housed under Specific Pathogen-Free (SPF) and non-SPF conditions.
- Induction of the "delayed death" phenotype using cyclophosphamide and fragmented dsDNA.
- Monitoring of animal survival, clinical symptoms, and hematopoietic stem cell differentiation.
Main Results:
- Mice under SPF conditions did not develop the characteristic symptoms or succumb to treatment.
- Opportunistic infections were identified as the major cause of systemic inflammation and sepsis in non-SPF mice.
- The failure of CD34(+) hematopoietic stem cells to differentiate into lymphoid progenitors occurred regardless of breeding conditions but was reversible by day 29.
Conclusions:
- Breeding conditions significantly influence the outcome of cyclophosphamide and dsDNA treatment, with SPF status protecting against mortality.
- Opportunistic infections are the key drivers of sepsis and inflammation in this model.
- The observed lymphoid differentiation defect is a consistent consequence of the treatment but can be restored over time.
