Utility of specific IgG4 response in saliva and serum samples for the diagnosis and follow up of human neurocysticercosis.

This study was aimed to analyze the Ig subtypes and IgG1 and IgG4 subclass responses to crude soluble extract (CSE) antigen and Ag B of Cysticercus cellulosae in pre and post treatment (PT) saliva and serum samples for the diagnosis and follow-up of neurocysticercosis (NCC) patients. Saliva and serum samples collected from 55 patients (15 highly suggestive of NCC clinically and radiologically, 10 hydatidosis, 10 other helminthic infections, 10 tubercular meningitis, 10 neurological disorders other than NCC), 15 normal healthy subjects and 10 NCC patients at 1, 3 and 6 months following albendazole therapy were analyzed for specific IgG, IgG1, IgG4, IgM and IgA antibody responses by ELISA. With the use of CSE Ag, the rank orders in saliva for sensitivity was IgG (71.4%) > IgG1 (68.2%) > IgG4 (65.2%) > IgM (57.7%) > IgA (55.5%) and specificity IgG1 = IgA (93.2%) > IgG = IgG4 = IgM (91.6%) while in serum, sensitivity was IgG (78.9%) > IgG1 (71.4%) > IgG4 (68.2%) > IgA (65.2%) > IgM (62.5%) and specificity IgG1 = IgG4 (90.2%) > IgA (85.9%) > IgG (83.3%) > IgM (82.1%). With the use of Ag B in saliva, the sensitivity was IgG (65.2%) > IgG1 = IgG4 (62.5%) > IgM = IgA (55.5%) and specificity with the use of saliva was IgG1 = IgG4 = IgM (94.8%) > IgG (93.2%) > IgA (91.6%) while with serum the sensitivity was IgG = IgG1 (68.2%) > IgG4 (65.2%) > IgA (62.5%) > IgM (57.7%) and specificity was IgG1 (93.2%) > IgG4 = IgM (91.6%) > IgA (90.2%) > IgG (87.3%). Comparative analysis of antibody responses in patients with single Vs multiple CT scan lesions indicated higher sensitivity in multiple lesion patients. Antibody responses in PT samples indicated that the undetectable IgG4, IgM and IgA responses in saliva samples correlated well with the CT scan reports while in serum samples, responses persisted longer. In conclusion, this study indicated that due to the lower sensitivity of IgM and IgA responses in pretreatment samples, detection of IgG4 subclass in saliva to either CSE Ag or AgB may serve better marker in the NCC follow-up.