Carbohydrates and the pathogenesis of Mycoplasma pneumoniae infection and AIDS--some observations and speculations.

Abstract

Carbohydrate-mediated interactions are prominent in the pathobiology of human infection with Mycoplasma pneumoniae. The mycoplasma uses specific long-chain sialo-oligosaccharides at the host-cell surface as receptors. These sialo-oligosaccharides contain I antigen in their backbones, and they are richly expressed at the primary site of infection--the ciliated bronchial epithelium--and on erythrocytes. The autoantibodies of high titers directed to I antigen, cold hemagglutinins, frequently produced in this infection are therefore antibodies to receptors and may be triggered by an autoimmunogenic mycoplasma-receptor complex in which the lipid-rich microorganism serves as an adjuvant. Current interest is focused on the possibility that the course of infection with human immunodeficiency virus type 1 (HIV-1) may be exacerbated by coinfection with mycoplasmas. One mechanism for such potentiation would be specific interactions between the mycoplasmas and HIV-1 leading to a concentration of the virus at the mycoplasmal surface. The envelope glycoprotein gp120 of HIV-1 is richly decorated with an array of oligosaccharides whose biosynthesis is host cell directed. By an analogy with M. pneumoniae, I propose that recognition of carbohydrates by various mycoplasmal copathogens is a potential mechanism for interactions with HIV-1.