Splenocyte blastogenesis suppressed in rats implanted with an osmotic pump

Area of Science:

• Immunology
• Pharmacology

Background:

• Systemic administration of immunomodulatory substances often utilizes osmotic pumps.
• The impact of the implanted device itself on immune function is not fully understood.

Purpose of the Study:

• To investigate the effects of empty osmotic pumps and catheters on rat splenocyte responsiveness.
• To explore the mechanisms behind pump-induced immune suppression.

Main Methods:

• Rats were implanted with empty osmotic pumps and catheters connected to jugular veins.
• Splenocyte responsiveness to bacterial lipopolysaccharide, pokeweed mitogen (PWM), and Concanavilan A was assessed in vitro.
• Lymphoid cell infiltration on pump surfaces and serum complement/corticosteroid levels were examined.

Main Results:

• Empty osmotic pumps and catheters significantly decreased splenocyte responsiveness to T and B cell stimulators.
• Immune suppression was comparable to endotoxin infusion and associated with lymphoid cell infiltration, particularly macrophages.
• Suppression was observed even with pyrogen-free saline infusion and was not linked to serum complement or corticosteroid alterations.

Conclusions:

• Implanted osmotic pumps and associated catheters can induce significant immune suppression independent of drug delivery.
• Lymphoid cell infiltration of the implant site appears to be a key factor in this immunosuppression.
• Understanding these device-related effects is crucial for interpreting studies using osmotic pumps for drug delivery.