Tissue histamine levels in male and female normal and nude mice.

In comparison with those in normal (+/+) mice, tissue histamine levels were lower in athymic (nu/nu) female mice and higher in athymic male mice. The sexual difference was less marked or absent in nu/nu mice. These results show (a) that endocrine factors are involved in the distribution of tissue histamine, and (b) that the thymus cannot be considered as the main source of tissue histamine in pathogen-free mice.