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RHINOVIRUSES AND THE IMMUNE SYSTEM
Rhinoviruses infect the epithelial cells of the respiratory tract. The viruses can be grouped according to the epithelial cell receptors to which
they bind. Major-group viruses bind to the cell surface receptor ICAM-1 for entry 
1 ; minor-group viruses bind to the unrelated low density
lipoprotein (LDL) receptor 
2 . This receptor difference turns out to be a key factor in how these viruses interact with the immune system.
Major-group viruses also bind the ICAM-1 molecule expressed on macrophages, dendritic cells, and other immune cells 
3 .
This attachment triggers a host of changes in the immune cells that effectively dampens the immune response. The immune cells produce
anti-inflammatory signals 
4 ; they are slower to activate the T cells in the lymph nodes that attack the viruses 
5 ; and they reduce the
production of antibodies and activation of memory B and T cells that protect the host against reinfection 
6 .
Because the minor-group viruses cannot bind the ICAM-1 molecule on immune cells, they do not suppress the immune system.
HUMAN RHINOVIRUSES
MINOR GROUP
MAJOR GROUP
ICAM-1
LDL
1

2

Epithelial cells of the airways
Macrophage
Macrophage
3

Dendritic
cell
Dendritic
cell
4

Anti-inflammatory
cytokines
THE SCIENTIST STAFF
Slows the
activation of
fighting T cells
(occurs in the
lymph nodes)
Pro-inflammatory
cytokines
Helper T
cell
5

Helper T
cell
Activation
of T cells
that fight invaders
(occurs in the
lymph nodes)
6

Slows and reduces the
production of antibodies
and memory B and T
cells that protect the host
against re-infection
B cells
Antibodies
B cells
Antibodies
Production of antibodies
and memory B and T
cells
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