CHARACTERIZATION OF INSULIN-LIKE GROWTH FACTOR-I RECEPTORS OF HUMAN ACUTE LYMPHOBLASTIC-LEUKEMIA (ALL) CELL-LINES AND PRIMARY ALL CELLS

The expression of insulin-like growth factor I (IGF-I) receptors (IGF-IR) on human B-lineage and T-lineage acute lymphoblastic leukaemias (ALL) representing different maturational stages has been studied. Immature stage I) and mature (stage II) T ALL as well as pre-B ALL cell lines expressed high numbers of IGF-IR with high affinity for IGF-I. In contrast, on T ALL, stage II and B ALL only low specific binding of I-125-IGF-I was detected. No binding of I-125-IGF-I to Burkitt lymphoma cells was found. Primary human T, pre-B and cALL cells also expressed IGF-IR with K(d) for IGF-I and IGF-IR number per cell in the same range as the investigated cell lines. Crosslinking of I-125-IGF-I to T and pre-B ALL cells revealed IGF-IR alpha-subunits of 135 and 116 kD for HSB2. Gene expression of IGF-IR could be detected in all T ALL cell lines but was indetectable in SKW6, a B ALL cell line.