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.