Developmental immunotoxicity investigations in the SD rat following pre- and post-natal exposure to cyclosporin.
BACKGROUND
The development and function of the immune system was assessed in juvenile SD rats following pre- or post-natal exposure to cyclosporin. The main objective was to assess the feasibility of the methods available for the detection of adverse effects on the development of the immune system for use in the safety assessment of medicines.


METHODS
In a pre-natal experiment, 15 pregnant rats were given 10 mg/kg/day of cyclosporin by gavage from day 6 of gestation until 4 days after parturition. A control group received olive oil. In a post-natal experiment, the pups from 35 litters were given 10 mg/kg/day of cyclosporin by gavage from 4 to 28 days of age. Half of the pups in each litter were given water and acted as controls. Immune endpoints were determined in the pups in both experiments from two to 10 weeks of age, including: lymphocyte subsets, serum immunoglobulin titres, serum autoantibodies, primary antibody response to sheep red blood cells (SRBC), delayed-type hypersensitivity response, humoral response to keyhole limpet haemocyanin, spleen cellularity, immune organ weights, and histopathology.


RESULTS
Pre-natal exposure caused no effects on immune function. Post-natal exposure caused immune depression during the treatment period and a persistent impairment of the immune system characterised by lymphoid hyperplasia in the spleen and a reduced primary antibody response to SRBC at 10 weeks of age.


CONCLUSIONS
These results demonstrate the importance of a post-treatment follow-up period in developmental immunotoxicity studies, in order to distinguish between the transient effects of immune modulation and the persistent consequences of developmental toxicity.
Barrow
Paul C
PC
MDS Pharma Services, Les Oncins, Saint-Germain sur l'Arbresle, France. paul.barrow@mdsinc.com
Horand
Françoise
F
Ravel
Guillaume
G
D000818:Animals; D000831:Animals, Newborn; D000917:Antibody Formation / Q000187:drug effects; D001323:Autoantibodies / Q000276:immunology; D001835:Body Weight / Q000187:drug effects; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects; D016572:Cyclosporine / Q000008:administration & dosage* / Q000633:toxicity*; D004342:Drug Hypersensitivity; D047108:Embryonic Development / Q000187:drug effects*; D004912:Erythrocytes / Q000276:immunology; D005260:Female; D046689:Fetal Mortality; D006968:Hypersensitivity, Delayed / Q000276:immunology; D018811:Maternal Exposure; D009929:Organ Size / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012756:Sheep; D013154:Spleen / Q000166:cytology / Q000187:drug effects* / Q000196:embryology
D001323:Autoantibodies; D016572:Cyclosporine