Strain- and Donor-Related Differences in the Interaction of Mycobacterium avium with Human Monocytes and its Modulation by Interferon- 

Abstract

Mycobacterium avium is a cause of disseminated infection in AIDS patients. The pathogenicity of M. avium for human monocytes was examined in an in vitro model. Peripheral blood monocytes obtained from 13 healthy donors were precultured for 2 days before infection. Monocytes were infected with six AIDS-associated and three non-AIDS-associated strains and four strains of M. avium selected on the basis of colonial morphology. Uptake of M. avium detected by counting intracellular acid-fast bacilli differed according to colonial morphology: Bacteria with round and opaque colony forms were phagocytosed more readily than those with flat colonies. Virulence as defined by intracellular growth was also partly associated with colonial morphology. Some but not all bacilli with flat colony forms multiplied in human monocytes; strains of the round opaque colonial form did not. The effects of recombinant human interferon-gamma on M. avium infection also were examined. Pretreatment of monocytes suppressed phagocytosis. After infection, coculturing usually augmented mycobacterial growth inhibition by human monocytes, but these effects were variable from strain to strain. Overall, interferon-gamma produced a small but statistically significant inhibition of intracellular growth in three of four strains tested.

A bone marrow-derived murine macrophage model for evaluating efficacy of antimycobacterial drugs under relevant physiological conditions

“…In the present study, as in other studies (36,40), it was found that the SmT variant SmT, LR114F, 101) generally tended to be more resistant to drugs in the broth assay, and this information is extended in the present study to show that the SmT isolates were often more resistant in the macrophage assay to drugs active against other morphological variants. Similar observations have been made with human monocytes (10,37).…”

Interleukin 12 at the site of disease in tuberculosis.

“…The results presented in this report provide new evidence that IL-12 consists of p40 and p35 chains, both of which are required for bioactivity (1 (26,27), IFN-'y reduces the bacillary burden in lepromatous leprosy patients (28) and is a functional marker of murine T cells that confer adoptive immunity against tuberculosis (29,30). TNF-a augments the mycobactericidal capacity of human macrophages ( 31 ) and is essential for granuloma formation to contain murine mycobacterial infection (32).…”

Modulation of the effector function of human monocytes for Mycobacterium avium by human immunodeficiency virus-1 envelope glycoprotein gp120.

“…Samples were harvested at time 0 (immediately after infection) and 7 d after infection for CFU assay. The density of monocyte monolayers as assessed by counting cell nuclei with naphthol blue black staining ( 19) was comparable between control and gp 1 20-pretreated cultures throughout the 7-d culture period.…”

“…Most M. avium growth using this experimental system is intracellular and not due to adherence ( 19 Counting ofAFB. Immediately after infection with M. avium, petri dishes were fixed with methanol and stained by Kinyoun's modified acid-fast method.…”