Detection of immune complexes in mice infected with Mycobacterium lepraemurium.

A specific binding test was used to detect immune complexes containing antigens of Mycobacterium lepraemurium in the serum and tissues of infected mice. Complexes were precipitated by antiserum against immunoglogulin, free antigen removed by washing and the presence of bound antigen demonstrated by measurement of uptake of radioactively labelled specific antibody by the precipitate. Tests were done both with 125I-labelled FAB prepared from an immune from rabbit antiserum against M. Lepraemurium and with 125I-labelled IgG precipitate. Out of seventy-nine serum samples taken monthly up to the 5th month after infection, only there were positive (one at 2 months and two at 3 months). Kidneys taken from infected mice were also examined for immune complexes. Although deposits of IgM and sometimes of IgG were observed by immunoflourescence in glomeruli of normal mice, deposits of IgG were more frequent later on in infected mice. Nevertheless, binding tests done on acid eluates were positive in only one out of fifty-three infected mice.