Papain and pepsin agglutinators showing specificity for autologous or homologous Fab and (Fab′)2 have been demonstrated in normal human and rabbit sera. In this study papain and pepsin agglutinators were shown to be present in normal rhesus serum. The evidence also suggests that these agglutinators are present in members of other families of the order Primates.

In a comparative study, individual sera from several members of Primates representing the families Hominidae, Pongidae, Cercopithecidae, Cebidae and the Prosimians were tested for agglutinator activity against the Fab and (Fab′)2 fragments of human and rhesus IgG. The pepsin agglutinators in each of the families studies reacted with rhesus (Fab′)2 fragments, but only members of the families Hominidae, Pongidae and Cercopithecidae reacted with human (Fab′)2 fragments. Human papain agglutinators were specific only for human Fab fragments. Likewise Cercopithecoid papain agglutinator reacted only with rhesus Fab fragments.


This study was supported by a United States Public Health Service Grant AI-07184 and a Robert A. Welch Foundation Grant, F-209.

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