Pleurodeles waltl (urodele amphibian) humoral immunity changes after a space flight

Previous studies reported important immunological changes after a space flight. However, most of these studies were focused on cellular immunity. To better understand what could be the effects of a space flight on the humoral immunity, we have analyzed the immunoglobulin heavy chain repertoire of adult P. waltl reared 1) on earth in classical conditions, 2) on board the MIR space station during five months (Perseus mission), and 3) on earth in the same conditions than those found on board MIR. P. walt was chosen for this study because this animal requires only limited care, thereby facilitating the work of the crew, and also because it was successfully used in previous missions. A prerequisite to this work was the knowledge of the number of immunoglobulin (Ig) isotypes, VH families, JH, and DH segments used by this amphibian. Once we had these data, we were able to analyze the level of transcription of Ig heavy chains, and the usage of the VH families in the three kinds of samples cited above. Our data revealed a strong increase in the level of IgY (IgG analogue), but not of IgM, heavy chain transcription in animals reared on board MIR. We also noted a profound change in the usage of the different VH families. A prolonged stay in space could therefore affect quantitatively and qualitatively the antibody production. Further studies will be necessary to evaluate the functional importance of these observations, and the time required to come back to a normal situation once back on earth. Finally, our experiments demonstrate that P. waltl is a useful model to study some of the physiological changes observed after a space flight.