Increase in specific binding of insulin-like growth factor (IGF) II to type 1 IGF receptors on erythrocytes of hypopituitary children receiving growth hormone therapy.

Specific receptor binding for insulin-like growth factors (IGFs) is measurable in young erythrocytes. Cells of similar age, Fraction A, can be reproducibly obtained by dextran gradient centrifugation from 5-10 ml of blood. We now report IGF-II specific binding to Fraction A erythrocytes from normal children and children with growth hormone deficiency. Normal controls (Group 1) were 5 male volunteers (14.7 +/- .6 years, mean +/- SEM) and 10 children with constitutional short stature (11.4 +/- 1.6 years) who had normal 6-hour daytime growth hormone profiles and plasma IGF-I values. Twelve growth hormone deficient children (Group 2), aged 13.7 +/- 1.1 years, had samples taken after 2 months without growth hormone therapy and again following 2 months with growth hormone (0.1 U/kg 3 times per week) therapy. The percent of total erythrocytes in Fraction A did not differ in the two groups of children. Group 1 had IGF-II specific binding of 10.2 +/- 0.6% (per 3 X 10(9) cells). IGF-II specific binding was less in Group 2 at 6.6 +/- 0.8% (p less than 0.002). With growth hormone therapy, IGF-II specific binding increased to 10.4 +/- 1.0% (p less than 0.02), a value not different from that seen in Group 1. Corresponding plasma IGF-II and IGF-I values showed a positive correlation with IGF-II specific binding (r = 0.54 and r = 0.56 respectively, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)