Antigen Immune Damage
Antigenic Variation
M. pneumoniae can rapidly alter their surface molecules to avoid detection by the host's immune system.
The membrane protein associated with invasiveness and its variation affects the toxicity of M. pneumoniae.
The molecular weight of the V-1 antigen in M. pneumoniae can alter and is linked with virulence
There is no toxicity or pathogenesis when the molecular weight of the V-1 antigen is 100-200kDa. Toxicity and pathogenesis has been observed at 30kDa.
The adsorption of red blood cells by M. pneumoniae alters the antigenicity of the red blood cell membrane, inducing autoantibody against red blood cell membrane I antigen, inducing autoimmune hemolytic anemia.
Immune Evasion
M. pneumoniae have varying surface membrane antigens to avoid the host’s immune system.
As the adhesion antigens of M. pneumoniae are polymorphic, it results in a decreased effect of specific antibodies.
Glycerophosphate on cell membranes of M. pneumoniae shares some antigenic component with host cells, which helps it avoid the host’s immune system.
These various evasion mechanisms allow M. pneumoniae to survive inside its host for long periods of time.
Cross Reacting Antigen
M. pneumoniae possess membrane antigens which imitate the red blood cell membrane I antigen. It also mimics antigenic components in Streptococcus pneumoniae 23 or 32 and M. genitalium.
M. pneumoniae membrane glycolipids also have a common antigen found in the brain and lung tissues, inducing cross reaction
P1 and P30 proteins in M. pneumoniae are similar to cytoskeletal proteins, fibrinogen, keratin and troponin in eukaryotes.
Consequently, when infection occurs, antibodies found in the lung tissues, the brain, red blood cell membrane, myocardial cells and lymphocytes, form antigen antibody complexes, exaggerating the immune response, which results in multisystem immune damage.
Immunosuppression
Studies have illustrated that M. pneumoniae can cause severe damage to B cells and T cells.
One study found that in individuals with M. pneumoniae infection, the amount of immunoglobulin G (IgG) decreased.
Another study found children with M. pneumoniae infections had decreased chemoattraction in neutrophils, decreased reactivity to phytohemagglutinin phytolectin and developed hypoglobulinemia.
These studies show M. pneumoniae cause reductions in immunoglobulin levels, strongly suggesting it is associated with immunosuppression.