Rada-Schlaefli replies
To the Editor:
Thank you for the opportunity to read and reply to the letter by Iyer, et al. As indicated in their letter, we inadvertently referred to detection of antibodies to Ag85 rather than antigen detection in citing their paper. Their interesting approach was designed to detect levels of secretory antigen and compare them with levels of cytoplasmic antigen in order to indirectly assess viability of Mycobacterium leprae. Unfortunately, Ag85 detection rates were quite low in untreated patients.
The results reported in our letter are clearly very preliminary since we did not have any follow-up data in treated patients. Whether or not the antibody response to excreted M. bovis antigen will be useful as an indirect marker of bacillary viability remains to be demonstrated with the followup studies. While significant levels of antibody may be more persistent than antigen, we are investigating whether a detectable decrease in these levels in a relatively short time, i.e., before multidrug therapy is completed, may be associated with a favorable clinical response.
Elsa Rada-Schlaefli, M.Sc.
Leprology and Experimental Pathology Laboratory
Institute de Biomedicina
Apartado 4043
Caracas 1010A, Venezuela