Growth hormone in T-lymphocyte thymic and postthymic development: A study in HIV-infected children

Growth hormone (GH) plays a role in thymic function, and recombinant GH may stimulate thymopoiesis in HIV-infected individuals. We performed immunologic analyses in 26 antiretroviral-treated children matched for age, pubertal status, clinical parameters, and antiretroviral exposure who did or did not show an impaired response to GH-release stimulation tests with arginine + GH-releasing hormone. The following abnormalities were found in GH-deficient compared with GH-nondeficient children after >4 years of therapy: CD4 count (P =. 02) and percentage (P =. 03), CD4 as percentage of normal cells for age (P =. 003), serum interleukin-7 concentration (P =. 02), and thymic volume (P =. 01). Naive CD4 (4+62+RA+ and 4+CCR7+RA+) and CD8 (8+CCR7+RA+) lymphocytes were lower in GH-deficient children (P =. 003; P =. 007; and P =. 02, respectively). Postthymic pathways were also impaired in GH-deficient children. Thus, central memory (4+CCR7+RA-) CD4+ cells were reduced (P =. 006), whereas effector memory (4+CCR7-RA-) CD4+ cells (P =. 002) and late effector CD8+ lymphocytes (8+CCR7-RA+ and 8+27-28-) (P =. 009 and P =. 002, respectively) were increased in these children. Growth hormone plays a role in thymic and postthymic pathways, and defective GH production may be associated with incomplete immunoreconstitution. Immunomodulant agents (including GH) could be useful in patients with defective GH production.