Primary Mycobacterium avium complex infections correlate with lowered cellular immune reactivity in Matschie's tree kangaroos (Dendrolagus matschiei)

The National Zoological Park has maintained a breeding colony of Matschie's tree kangaroos (Dendrolagus matschiei) since 1975 with a documented histor y and continued prevalence of Mycobacterium avium complex (MAC) infections. No evidence of immunosuppressive retrovirus infections or loss of heterozy gosity that may have led to an immune dysfunction in these animals was foun d. Isolates of MAC organisms from affected tree kangaroos and from their en vironment had no common restriction fragment DNA types. Cellular immune rea ctivity in apparently healthy tree kangaroos was 3- to 6-fold lower than in humans and other marsupial and eutherian mammals, as determined by lymphoc yte proliferative assays. Thus, while MAC infections are typically opportun istic in humans and other mammals, tree kangaroos commonly develop primary progressive disease with MAC from random sources. Comparative information d erived from this study should benefit both the endangered tree kangaroo and humans with immunosuppressive disorders that lead to mycobacterial infecti ons.