Patterns of antibody and serum proteins in experimentally induced human malaria

Abstract
892 sera from 90 volunteers infected with Plasmodium falciparum or P. vivax were examined for the presence of antibodies to malaria by using the IFA technique with fluorescein-labelled IgA, IgG, and IgM conjugates. In addition, the changes in the alpha, beta, and gamma globulin levels were determined by means of electrophoretic separation on cellulose acetate. The results indicated that the IgG response rose to the highest level and persisted the longest time. Compared to the IgG response, the IgA and IgM responses were more transient, and after a relatively short time returned to near pre-inoculation levels. This drop occurred even in the presence of persistent parasitaemia. The changes in the alpha, beta, and gamma globulin percentage curves occurred primarily during the early periods after infection. The changes were most prominent between days 9 and 11 in the blood-induced infections and at approximately day 16 in those infected by sporozoites. The IFA test continued to measure changes in the IgA, IgG, and IgM antibody responses to the malaria parasite long after the alpha, beta, and gamma globulin percentages had returned to pre-inoculation levels.