Gamma-globulin enhances survival in pneumococcal-challenged asplenic infant rats

Early augmentation of a patient's immune system can be a valuable adjunct to standard supportive and antibiotic treatment of overwhelming postsplenectomy sepsis (OPSS). Normal humoral immune factors against pneumococcal sepsis are replenished by the parenteral administration of human gamma-globulin (HGG). Monthly prophylactic administration of HGG to asplenic individuals to prevent OPSS has been suggested. The cost of such measures is prohibitive, and the risk of serum-transmitted disease is significant. We administered HGG to splenectomized infant rats with pneumococcal sepsis to determine if mortality rates could be reduced and survival time prolonged. Fifty-six three-day-old rats underwent splenectomy and another 56, laparotomy without splenectomy. Twenty-eight animals from each operative group were administered HGG and the other 28, human serum albumin (HSA), 12 and 24 hours after inoculation with varying dosages of log-phase Streptococcus pneumoniae. The LD50 for asplenic animals was less than 50 colony forming units (cfu) per animal, while for the group with spleens, the LD50 was 250 to 500 cfu. There were no significant intragroup variations in LD50 between HGG and HSA subgroups. Survival times were compared using the BMDP1L-Life Tables and Survival Functions, and the generalized Wilcoxon t-test. These data show that host immunity to pneumococcal challenge in asplenic infant animals might be fully restored by the administration of HGG, even after the onset of symptoms. Survival of an asplenic child with evidence of OPSS might be enhanced by immediate administration of HGG.