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An indirect immunofluorescence technique was developed for the detection of antibodies to dsDNA and the simultaneous assessment of antinuclear antibodies 'in toto' (ANA). This assay was based upon the use as substrate of smears of peripheral blood derived from rats infected with Trypanosoma lewisi. T. lewisi possesses a giant kinetoplast posteriorly to the nucleus. Enzyme digestion and absorption experiments provided strong evidence that T. lewisi kinetoplast contains dsDNA uncontaminated by other nuclear antigens. The T. lewisi immunofluorescent test was evaluated on a total of 130 sera (30 from patients with SLE) and compared with radioimmunoassays for antibodies to dsDNA ([125I]dsDNA-RIA) and antibodies to ssDNA ([125I]ssDNA-RIA). Excellent correlation was found between kinetoplast immunofluorescence and [125I]dsDNA-RIA, whereas no non-SLE sera showing significant ssDNA binding activity gave kinetoplast staining. With a single exception, only SLE sera reacted with T.lewisi kinetoplast. Sera containing autoantibodies other than ANA did not induce fluorescence of any part of the parasite, including the flagellum and its base. These results indicate that the T. lewisi immunofluorescence test is specific and reliable, and combines the advantages of Crithidia luciliae with those of Trypanosoma gambiense. It may be used routinely for evaluation of total ANA and simultaneous detection of antibodies against dsDNA.

Division of Trypanosoma lewisi in the rat is terminated by ablastin, a factor(s) in the serum of rats acquired during infection which is believed to be specific antibody. In this study a semi-automated microassay technique for the measurement of ablastin is described. The system involved the use of [3H]TdR as a marker for trypanosome division and a multiple-well cell harvester to harvest trypanosomes from wells of microtitre plates. The method is versatile, quantitative and easy to perform, permitting the simultaneous measurement of numerous samples for this division-inhibitory activity.

The effects of trace metal contaminants (lead, cadmium, and mercury) on the immunologic responses of rats infected with Trypanosoma lewisi were investigated to determine whether chronic exposures to subclinical levels of these metals have adverse effects on the host's ability to respond to an infective agent.Earlier and higher levels of parasitemia were detected in animals exposed to cadmium, lead, and mercury. The variability in length of trypanosome cells in metal-exposed animals became constant at a later time and persisted for a longer time, indicating a delay in antibody synthesis. Serum levels of IgG and IgM were increased in infected animals exposed to trace metals; however, lower levels were observed when compared with infected control animals. Animals exposed only to trace metals showed decreases in serum levels of IgG and IgM. In contact sensitivity to dinitrofluorobenzene (DNFB), animals exposed to trace metals demonstrated no significant difference in sensitization when compared with those infected and exposed to trace metals.