Humoral immune response in patients with cerebral parenchymal cysticercosis treated with praziquantel.

The humoral immune response to treatment with praziquantel (PZQ) was studied in eight patients with parenchymal cerebral cysticercosis (CC). In the serum and in the cerebrospinal fluid (CSF) before, during and after the administration of the drug, the following were quantitated (a) levels of specific anticysticercous antibodies measured in optical densities by the ELISA method; (b) levels of IgG, IgM, IgA and IgE; (c) levels of complement fraction C3, C4; (d) presence of immune complexes; (e) total number of white blood cells in the CSF. It was found that after treatment with PZQ, the level of specific anticysticercous antibodies and the level of IgG rose significantly in the CSF but not in the blood. The levels of the fractions of the complement and the immunoglobulins IgM, IgA and IgE did not change significantly either in the serum or in the CSF. The blood-brain barrier was found ruptured in three patients before therapy and in five patients after the therapy as measured by the albumin index. Nevertheless, the IgG index showed that there was local production of IgG in five patients before treatment and in seven after the end of it. The relative specific antibody index was greater than 1.0 in five patients before therapy and in seven after therapy. This data strongly supports the idea that the specific antibodies are produced intrathecally and are not derived from the serum pool through a ruptured blood-brain barrier. It was concluded that patients with parenchymal CC have an elevation of specific anticysticercous probably due to a combination of a ruptured blood-brain barrier and intrathecal synthesis. The relatively small rupture of the blood-brain barrier and the high IgG and relative specific antibody index suggest that intrathecal synthesis is the most important mechanism. The humoral immune response may be of importance not only in the elimination of the parasite but also in the genesis of the illness.