The objective of a study by LeRoith et al. (A-68) was to evaluate the effect of a 7-week administration of recombinant human GH (rhGH) and recombinant human insulin-like growth factor (rhIGF-I)

separately and in combination on immune function in elderly female rhesus monkeys. The assay for the in vivo function of the immune system relied on the response to an immunization with tetanus toxoid. The following are the responses for the three treatment groups and a control group:

Saline rhIGF-I rhGH rhIGF-I þ rhGH 11.2 12.2 12.15 11.5 9.0 9.4 11.20 12.4 10.8 10.7 10.60 10.8 10.0 10.8 11.30 11.9 9.1 11.00 11.0 12.6 Source: Data provided courtesy of Dr. Jack A. Yanowski.