Artificial fatty acylation of proteins has attracted significant attention during the last decade as a method for modification of protein specificity and efficacy of action on mammalian cells (A. V. Kabanov and V. Yu. Alakhov (1994) J. Contr. Release 28, 15-35). Horse radish peroxidase (HRP) is used in this work to study the interaction of a fatty acylated protein with various mammalian cells. The HRP is modified with the chloranhydride of the stearic acid in the reversed micelles of sodium bis-(2-ethylhexyl)sulfosuccinate (Aerosol OT) in octane, a convenient protocol allowing production of protein molecules with a controlled, low modification degree (A.V. Kabanov et al. (1987) Ann. N. Y. Acad. Sci. 501, 63-66). The influence of the hydrophobic group on the binding and internalization of HRP in MDCK, P3-X63-Ag8, CHO, and HepG2 cells is examined. The major results are as follows: (i) the fatty acylation of a protein significantly enhances its binding to all tested mammalian cell lines, with a line-specific efficiency; (ii) the binding efficiency can be modified by changing growth conditions in a defined medium; (iii) along with the enhancement of protein adsorption on the plasma membrane, fatty acylation increases internalization of the protein during incubations at 37 degrees C; (iv) internalized protein was observed in endocytic vesicles; no evidence was obtained for a cytoplasmic distribution. These results are discussed in connection with previously observed effects of the fatty acylated proteins on cell activity.

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Visceral leishmaniasis, a chronic and often fatal disease, is caused by the protozoan parasite Leishmania donovani. Both specific and nonspecific antibodies are produced in the course of the disease, and autoantibodies may be involved in pathogenesis. Tubulin and actin have been found to be associated with L. donovani. To learn whether antiactin and antitubulin antibodies are present in visceral leishmaniasis, we tested sera from 263 infected dogs by enzyme-linked immunosorbent assay for antibodies to the antigens L. donovani, actin, and tubulin. All samples reacted positively with L. donovani, and a high percentage reacted positively with all three antigens. Sera from 202 uninfected dogs were also tested, none reacted with L. donovani antigen, although positive reactions were observed for 8 of the samples with actin or tubulin. It was found that the antibodyantigen reaction occurred at the Fab portion of the immunoglobulin molecule. Competitive enzyme immunoassays showed that the reaction was inhibited if the positive serum was first incubated with L. donovani antigen, actin, or tubulin and then tested by enzyme-linked immunosorbent assay. These results suggest that antiactin and antitubulin antibodies are present in the sera of dogs infected with visceral leishmaniasis.