Influence of insulin-like growth factor-I antiserum to proliferation of T-cell receptor-activated human T-lymphocytes

We have previously reported that Insulin-like growth factor (IGF-I) is a cellular growth factor of human transformed T-lymphocytes. To evaluate the role of IGF-I for nontransformed T-cells we investigated synthesis of IGF-I and the influence of an IGF-I antiserum, UBK487, during proliferation process. IGF-I is synthesized by B-lymphocytes and monocytes during proliferation. Via the T-cell receptor (CD3 subunit) induced proliferation of resting T-cells was inhibited by addition of UBK487. The addition of monocytes to the resting T-cell fraction reversed the UBK487 effect. Using UBK487, a 12 kDa protein could be immunoprecipitated from unstimulated or PHA stimulated T-cells whereas a 36 kDa protein could be immunoprecipitated from OKT3 stimulated T-cells.