Humoral Immune Response in Tuberculous Pleuritis

Tuberculous pleuritis is a good human model to understand the local and protective immune \nresponse against tuberculosis, due to the self-limitedness of the disease. Although the cellular immune \nresponse has been well characterised in tuberculous pleurisy, much less is known about the humoral \nimmune response operating at the site of infection. To understand the humoral immune response, B \ncells were enumerated in peripheral blood mononuclear cells (PBMC) and pleural fluid mononuclear \ncells (PFMC) of tuberculous (TP) and non-tuberculous pleuritis patients (NTP). The levels of IgG, IgA \nand IgM antibodies for PPD, culture filtrate (CF) and sonicate antigens (Son Ag) were assessed in \nplasma (BL) and pleural fluid (PF) and a western blot was carried out with the CF antigen. The \npercentage of CD19+B-cells was similar in PBMC and PFMC of TP patients but was significantly \nlower in PFMCs of NTP patients. The IgG levels for PPD and CF antigens were higher in PF of TP \nthan NTP patients. The antigen recognition patterns did not differ in plasma and pleural fluid of the \nsame patient in both groups pointing out the passive diffusion of the plasma to the pleura. The antigens \n25, 31, 33, 70, 110, 124 and 132 kDa were recognized exclusively by the TP patients. Thus our study \nshowed that the local humoral response in TP did not differ from the systemic response. However, the \nhumoral response differed in TP patients when compared to NTP patients.