Changes in lymphoid organs of Ames dwarf mice after treatment with growth hormone, prolactin or ectopic pituitary transplants.

This study was performed to obtain more insight into the roles of PRL and GH in the control of immune functions in hereditary dwarf mice characterized by severe immunodeficiency. Adult female Ames dwarf mice (df/df) were injected daily for 10 days with ovine PRL (oPRL), bovine GH (bGH), oPRL+bGH or were implanted with a normal pituitary under the kidney capsule for 5 days. Only the treatment with bGH resulted in significant increases in the gain of body weight, and in absolute and relative thymus and spleen weights. Treatment with oPRL alone did not affect body weight gain or thymus and spleen weights. Treatment with oPRL+bGH produced a significant increase in the gain of body weight and in absolute and relative spleen weight but these effects were smaller than those measured in dwarf mice treated with bGH alone. Only bGH therapy resulted in extensive recovery of the absolute number of lymphocytes in the thymus and spleen of dwarf mice, with the values in treated dwarf mice not significantly different from those found in normal non-dwarf females. However, when these values were corrected for body weight, both the splenic and the thymic indices exceeded the values found in normal mice. The absolute numbers of lymphocytes in the spleen were also increased by oPRL+bGH treatment, but did not reach the values found in normal mice; however, the splenic index exceeded the values found in normal animals. Surprisingly, the absolute and relative numbers of lymphocytes found in the thymus of dwarf mice under oPRL+bGH therapy were indistinguishable from those found in oPRL or vehicle treated dwarf mice.(ABSTRACT TRUNCATED AT 250 WORDS)