Effect of ambient temperature on phenotype and functions of professional phagocytes of athymic nude mice

Cytofluorometric analysis of surface marker expression was performed on myeloid cells isolated from bone marrow, spleen and lymph nodes of nude mice and nu/+ and +/+ mice (haired controls) exposed for various time periods to ambient temperature of 22°C or 28°C. A rise in the proportion of cells bearing macrophage markers (MAC-1, MAC-3 and F4/80) in the spleen and of FcR+ cells in all tissues tested was found in 22°C-exposed nudes with high nonshivering thermogenesis. Numbers of MAC-1+ macrophages and actively phagocytic cells increased also in peritoneal exudates. There was a conspicuous predominance of large macrophages in the exudates and the specific markers decreased in density on their surface. Ia expression declined in all tissues tested with the length of exposure to cold. In the granulocytic series (BP-2+ cells), there was a decrease in the bone marrow and lymph nodes and an increase in the spleen and circulation, which suggested an enhanced mobilization and increased production at extramedullary sites in cold-exposed nude mice. The changes in haired mice were negligible.