Suppression of immune response to Listeria monocytogenes: mechanism(s) of immune complex suppression

Abstract

We have investigated possible mechanisms underlying immune complex suppression of resistance to Listeria monocytogenes. Inhibition of resistance was found when immune complexes were formed in vivo in immune mice or in nonimmune mice adoptively transferred with specific antibody. Suppression was also found when nonimmune mice were injected with immune complexes preformed in vitro. We investigated the role of complement by decomplementing mice with cobra venom factor purified by high-pressure liquid chromatography. Complete depletion of serum C3 did not eliminate immune complex suppression of resistance to L. monocytogenes, suggesting that complement activation is not required for immune complex suppression. Infection-induced changes in the surface phenotype and functional properties of macrophages from normal and immune complex-suppressed mice were also investigated. Macrophage expression of both H-2K and Ia molecules increased during the response of normal mice to L. monocytogenes. However, these changes were not found in immune complex-suppressed mice. In contrast, membrane interleukin 1 expression was increased in macrophages from suppressed mice compared with macrophages from normal mice. Macrophages from L. monocytogenes-infected normal and immune complex-suppressed mice expressed cytotoxicity against tumor cells in vitro. We conclude that immune complexes do not inhibit resistance to L. monocytogenes by activation of complement or decreasing macrophage cytotoxic activity. Rather, defects in Ia expression by macrophages from suppressed mice might be one component responsible for immune complex suppression of resistance to L. monocytogenes.

Cytolytic activity against mycobacterial antigens: differences between haemophiliacs with and without HIV infection

“…Since immune response to infection with LM can be suppressed by giving a secondary challenge with protein antigen at the time of infection with LM, leading to a high susceptibility to infection [14]. This suppression may be mediated through immune complexes, by directly inhibiting macrophages, or binding to Fc receptors.…”

Aggregated Immunoglobulin Protects Immune T Cells from Suppression: Dependence on Isotype, Fc Portion, and Macrophage FcγR

“…Regulation of the immune response by antigen-antibody (Ag-Ab) immune complexes (IC) has been a subject of interest for many years [13][14][15][16][17][18]. An extensive literature indicates the potential role of circulating IC in the pathogenesis of different infections, cancers, and autoimmune phenomena [19][20][21].…”

“…An extensive literature indicates the potential role of circulating IC in the pathogenesis of different infections, cancers, and autoimmune phenomena [19][20][21]. In both humoral and cell-mediated immunity, IC are often potent tolerogens [13,17,19], or to the contrary, can enhance immunity [14,19]. These opposite effects are dependent on several factors, such as the size and valency of antigen or antibody, the Ag/Ab ratio, antibody isotype and affinity, the immune status of the host, and the integrity of the antibody molecule [17,19].…”

“…In both humoral and cell-mediated immunity, IC are often potent tolerogens [13,17,19], or to the contrary, can enhance immunity [14,19]. These opposite effects are dependent on several factors, such as the size and valency of antigen or antibody, the Ag/Ab ratio, antibody isotype and affinity, the immune status of the host, and the integrity of the antibody molecule [17,19]. The immunomodulatory effect of IC, can be either antigen-specific, or nonspecific, or a combination of both [16,17,19].…”

“…These opposite effects are dependent on several factors, such as the size and valency of antigen or antibody, the Ag/Ab ratio, antibody isotype and affinity, the immune status of the host, and the integrity of the antibody molecule [17,19]. The immunomodulatory effect of IC, can be either antigen-specific, or nonspecific, or a combination of both [16,17,19]. Since two separate components form IC, then antigen and antibody can affect the immune response, independently or discordantly, or in unison, and their action also is dependent to a great extent on the target cell.…”