Visceral leishmaniasis in Somalia. Significance of IgG subclasses and of IgE response

We have determined the levels of IgG subclasses and IgE as well as specific antibodies of these isotypes in sera from 22 patients with clinical visceral leishmaniasis (VL) from Somalia. The results are compared with those obtained from 30 Somali and 23 Swedish controls. We found markedly increased concentrations of IgG1 in the VL sera, indicating that the pronounced increase in IgG in VL which is generally considered to be due to polyclonal B-cell activation is mainly restricted to this subclass. The IgG2 concentrations were significantly decreased. The IgG3 and IgG4 concentrations, on the other hand, did not differ between the two groups of Somali sera. The Somali control sera contained higher concentrations of IgG1 and IgG3, but significantly lower concentrations of IgG2 as compared to Swedish controls. The IgG4 values, on the other hand, were not different between the two groups of control sera. Anti-leishmania antibodies belonging to all IgG subclasses, were found in the patients' sera. There was no significant difference in total IgE between sera from VL patients and controls and specific IgE antibodies were only detected in a few patients. The Western blot assay (WB), revealed the presence of two bands corresponding to 74 kDa and 88 kDa in all patients' sera, indicating a possible diagnostic role for WB in this particular population.