A quick method of demonstrating bacillaemia in patients with lepromatous leprosy and ultrastructural studies of the circulating acid-fast bacilli

While studying circulating immune complexes (CIC) in the sera of lepromatous patients by the polyethylene glycol (PEG) precipitation technique, we found (by light microscopy) abundant acid-fast bacilli (AFB), morphologically similar to those seen in slit skin smear preparations from these patients, precipitated with the PEG precipitated materials. Both solid and non-solid AFB could be readily identified. Ultrastructures of these AFB in the PEG aggregates showed some similarity with those detected in the PEG precipitates prepared from armadillo-derived lepromin under identical conditions. The most striking difference between the AFB in the test sera and that in the armadillo-derived lepromin was the absence of any transverse band in the former. This suggested that the AFB in the patients' circulation were not in division stage. Furthermore, electron-dense material were deposited on the AFB co-precipitated from the patients' sera, which were not found on the AFB co-precipitated from the armadillo-derived lepromin.