Serum IgE and IgG4 against muscle larva excretory-secretory products during the early and late phases of human trichinellosis

In human trichinellosis, the relevance of the presence and persistence of specific serum IgE and IgG4 during the early and late phases of infection is still controversial. The aim of this work was to determine the percentage of human sera presenting IgE and IgG4 against Trichinella spiralis muscle larvae excretory-secretory products as well as their levels during the early and late phases of the infection. The antigen recognition pattern by serum total immunoglobulins (IgGAM), IgE, and IgG4 was assessed over time. Serum samples during early and late phases were analyzed by ELISA and immunoelectrotransfer blot (IETB). Results showed that (a)-IgE and IgG4 are present at constant levels in both phases; (b)-IgE recognized the glycoproteins of similar to 45 and similar to 55 kDa and IgG4 only the similar to 45 kDa; (c)in the late phase, the percentage of specific IgE positive sera was higher than that of specific IgG4 by IETB; while in serum samples taken during the early phase, no differences were found between both isotypes; (d)-both isotypes displayed different glycoprotein recognition patterns: the pattern corresponding to IgE was coincident with that of IgGAM, comprising seven glycoproteins (ranging from similar to 116 to similar to 29 kDa), whereas IgG4 revealed four glycoproteins (ranging from similar to 97 to similar to 45 kDa), showing a different sera recognition percentage depending on the phase studied. In conclusion, IgE and IgG4 cannot be considered exclusive isotypes of neither the early nor the late phase of infection and they are as useful as the detection of total antibodies in the early diagnosis.