Immunological survey in high altitude: effect on antibody production and the complement system.

In order to asses the effect of acute exposure to natural high altitude on some immunological mechanisms of mice, the primary response to SRBC was studied by the direct Hemolytic Plaque and Hemagglutination Tests. A control group was studied in Lima, Peru, 150 m. At high altitude (Ticlio, Peru, 4843 m), we found fewer spleen plaque-forming cells (PFC) and the maximal peak of PFC was delayed 1 day, as compared with the response at a lower altitude. Conversely, there was a higher serum concentration of 2-ME sensitive and resistant hemagglutinin antibodies at high altitude and the 19-S (2-ME sensitive) response was predominant during the first days at high altitude while the 7-S response was retarded. These results are interpreted as a stimulating effect of hypoxia on the 19-S antibody production rather than a cellular proliferation as far as the SRBC system is concerned. Serum concentrations of Igs G, M, A and the fraction C'3 of the Complement (B1C/B1A globulin) were determined in normal natives from three cities at different altitude levels: Morococha-Ticlio, 4680 m; La Oroya, 3700 m; and Tarma, 3051 m by the Radial Immunodiffusion Test. The serum concentration of C'3 was correlated with the total hemolytic activity of Complement (C'H50 method) in a group of natives from Morococha. The control group was of normal natives from Lima. No significant differences were found between resum concentration of Igs G, M and A in both groups, but there was a tendency for higher values of IgA at higher altitudes, and most sera in the high altitude group were above the normal IgG values for adults. The resum concentration of C'3 and the hemolytic activity of Complement were wound to be diminished in the high altitude group. These results are interpreted as an inhibitory effect of the altitude on the sequential activation and/or lysing capability rather than a reduction in the C'3 concentration.