Expression of type I insulin-like growth factor receptors on human peripheral blood mononuclear cells.
Insulin-like growth factor-I and -II (IGF-I and IGF-II), both of which bind to type I IGF receptors, can modulate certain functions of the immune system. We, therefore, studied the expression of type I IGF receptors on purified subpopulations of peripheral blood mononuclear cells. Using two-color flow cytometry, specific binding of a monoclonal antibody directed against the type I IGF receptor (alpha IR3) was found in every subpopulation. Relatively high numbers of receptors were detected on monocytes, natural killer cells, and CD4+ T-helper cells, an intermediate number of receptors on CD8+ suppressor/cytotoxic T-cells, and a relatively low number of receptors on B-cells. The presence of these receptors was confirmed by specific binding of [125I] IGF-I to purified subpopulations. alpha IR3 inhibited the binding of [125I] IGF-I. The specific binding of [125I]IGF-I to monocytes could be completely inhibited by IGF-II and insulin, but higher doses of these peptides were needed than of IGF-I. Scatchard analysis revealed the presence of 734 +/- 426 receptors/monocyte, with a Kd of 0.23 +/- 0.05 nM. A lower number of receptors (230 +/- 52), but with a higher affinity (Kd = 0.05 +/- 0.02 nM), was found on purified T-cells. The positive effect of IGF-I on natural killer cell cytotoxicity indicates that the type I IGF receptors on this cell type are functional. The possibility that IGF-I mediates hormonal effects on the immune system is discussed.
Kooijman
R
R
Department of Immunology, University Hospital for Children and Youth, Het Wilhelmina Kinderziekenhuis, Utrecht, The Netherlands.
Willems
M
M
De Haas
C J
CJ
Rijkers
G T
GT
Schuurmans
A L
AL
Van Buul-Offers
S C
SC
Heijnen
C J
CJ
Zegers
B J
BJ
D001402:B-Lymphocytes / Q000737:chemistry / Q000276:immunology / Q000648:ultrastructure; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007457:Iodine Radioisotopes; D007694:Killer Cells, Natural / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D007963:Leukocytes, Mononuclear / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D009000:Monocytes / Q000737:chemistry / Q000276:immunology / Q000648:ultrastructure; D017526:Receptor, IGF Type 1 / Q000032:analysis* / Q000378:metabolism; D013601:T-Lymphocytes / Q000737:chemistry / Q000276:immunology / Q000648:ultrastructure
D015704:CD4 Antigens; D016827:CD8 Antigens; D007457:Iodine Radioisotopes; D017526:Receptor, IGF Type 1