title: Interleukin 7 and interleukin 4 stimulate human thymocyte growth through distinct mechanisms.
abstract: One of the major functions of cytokines is their ability to regulate cell growth and differentiation. The complexity of this process has been highlighted by recent studies on murine thymocytes; it has been shown that a number of cytokines interact to regulate thymocyte growth. We have investigated the effects of interleukin 4 (IL-4) and interleukin 7 (IL-7) on human thymocyte proliferation. Although maximal proliferation was dependent upon the presence of the mitogen phytohaemagglutinin (PHA), IL-7 alone stimulated thymocyte growth. In order to determine if this proliferation was due to the induction of IL-2, this pathway was inhibited by the addition of blocking antibody to the IL-2 receptor. Proliferation induced with IL-7 plus PHA, but not that induced by IL-7 alone, could be blocked by this treatment. In contrast, IL-4 stimulated thymocyte proliferation only in the presence of PHA; this proliferation was not inhibited by antibodies to the IL-2 receptor. Our findings show that both IL-7 and IL-4 can act as growth factors for human thymocytes, and that these cytokines stimulate proliferation through distinct mechanisms.
authors.affiliation: Charing Cross Sunley Research Centre, Hammersmith, London.
authors.forename: C
authors.initials: C
authors.lastname: Varma
authors.forename: D
authors.initials: D
authors.lastname: Chantry
authors.forename: F
authors.initials: F
authors.lastname: Brennan
authors.forename: M
authors.initials: M
authors.lastname: Turner
authors.forename: F
authors.initials: F
authors.lastname: Katz
authors.forename: M
authors.initials: M
authors.lastname: Feldmann
mesh_terms: D002455:Cell Division / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology*; D015851:Interleukin-7 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D010835:Phytohemagglutinins / Q000494:pharmacology; D015375:Receptors, Interleukin-2 / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects*; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D007376:Interleukin-2; D015851:Interleukin-7; D010835:Phytohemagglutinins; D015375:Receptors, Interleukin-2; D015847:Interleukin-4