Immune Response to Infection and Disease
A striking feature of immunity in filarial infections is the long term balanced relationship between the host and the parasite. Following infections high levels of anti-parasite IgE and IgG4 are produced which is generally accompanied by eosinophilia. This is due to the preferential stimulation of T-cells which produce IL-4 and IL-5(Th-2 type). IL-4 is known to promote B cell class resulting in IgG4 and IgE production. This condition is mainly seen in asymptomatic microfilaraemics. The IgG4 acts as "blocking antibody" and thereby reduces the inflammatory activity of IgE.

The development of pathology is also associated with th-1 type response and high level of IgE, IgG1, IgG2 and low IgG4. Elephantiasis may result from killing of late stage larval antigens by IgE mediated mechanisms or by a passive reaction of naturally dying adult worms, evoking IgG1 and IgG2 antibody response which mediate inflammatory reactions.

The patients with tropical pulmonary eosinophilia elicit a very high IgE response which is predominantly developed against microfilaria. In TPE mf are not found since the immunological hyper-responsiveness removes this stage of the parasite from circulation.

 

Last Updated on:06/05/2014