Human innate immunity under the conditions of five-day dry immersion

The system of congenital immunity was studied in 12 apparently healthy men 18 to 26 years of age subjected to five-day dry immersion without the use of countermeasures. Peripheral blood was analyzed for monocytes, granulocytes, and lymphocytes expressing the TLR²⁺, TLR⁴⁺, TLR⁶⁺, CD11b⁺, CD¹⁴⁺, CD¹⁶⁺, CD¹⁸⁺, CD²⁴⁺, CD³⁶⁺, CD⁵⁴⁺, CD⁵⁶⁺, and CD²⁰⁶⁺ receptors. Expression of the early activation marker CD69 on natural killer cells was studied in unstimulated and interleukin-2-activated mononuclear cell cultures. The negative shifts in the congenital immunity system in some volunteers at the end of immersion and during recovery can be regarded as warnings about the depletion of the system’s reserves and the increase of the risk of infectious diseases, such as those caused by normal microflora, which typically does not provoke pathological reactions in the host.