Role of B-1 cells in the immune response against an antigen encapsulated into phosphatidylcholine-containing liposomes.

B-1 lymphocytes comprise a unique subset of B cells that differ phenotypically, ontogenetically and functionally from conventional B-2 cells. A frequent specificity of the antibody repertoire of peritoneal B-1 cells is phosphatidylcholine. Liposomes containing phosphatidylcholine have been studied as adjuvants and their interaction with dendritic cells and macrophages has been demonstrated. However, the role of B-1 cells in the adjuvanticity of liposomes composed of phosphatidylcholine has not been explored. In the present work, we studied the contribution of B-1 cells to the humoral response against ovalbumin (OVA) encapsulated into dipalmitoylphosphatidylcholine (DPPC) and cholesterol-containing liposomes. BALB/X-linked immunodeficient (xid) mice, which are deficient in B-1 cells, showed quantitative and qualitative differences in the anti-OVA antibody response compared with wild-type animals after immunization with these liposomes. The OVA-specific immune response was significantly increased in the BALB/xid mice when reconstituted with B-1 cells from naive BALB/c mice. Our results indicate the internalization of DPPC-containing liposomes by these cells and their migration from the peritoneal cavity to the spleen. Phosphatidylcholine significantly contributed to the immunogenicity of liposomes, as DPPC-containing liposomes more effectively stimulated the anti-OVA response compared with vesicles composed of dipalmitoylphosphatidylglycerol. In conclusion, we present evidence for a cognate interaction between B-1 cells and phosphatidylcholine liposomes, modulating the immune response to encapsulated antigens. This provides a novel targeting approach to assess the role of B-1 cells in humoral immunity.

Immunomodulation of Homeopathic Thymulin 5CH in a BCG-Induced Granuloma Model.

The present study analyzed the immune modulation mechanisms of thymulin 5CH in a granuloma experimental model. Male adult Balb/c mice were inoculated with BCG into the footpad to induce granuloma, which was quantitatively evaluated. The phenotypic characterization of phagocyte, T- and B-lymphocyte populations in the peritoneum, and local lymph node was done by flow cytometry. During all experimental periods, thymulin 5CH and vehicle (control) were given ad libitum to mice, diluted into the drinking water (1.6 × 10(-17) M). After 7 days from inoculation, thymulin-treated mice presented reduction in the number of epithelioid cytokeratine-positive cells (P = 0.0001) in the lesion, in relation to young phagocytes. After 21 days, the differentiation of B1 peritoneal stem cells into phagocytes reached the peak, being higher in thymulin-treated mice (P = 0.0001). Simultaneously, the score of infected phagocytes in the lesion decreased (P = 0.001), and the number of B1-derived phagocytes, CD4+ and CD8+ T lymphocytes in the local lymph node increased in relation to control (P = 0.0001). No difference was seen on the CD25+ Treg cells. The results show that thymulin 5CH treatment is able to improve the granuloma inflammatory process and the infection remission, by modulating local and systemic phagocyte differentiation.

Paracoccidioides brasiliensis GP43-derived peptides are potent modulators of local and systemic inflammatory response.

Paracoccidioidomycosis is a systemic granulomatous disease caused by the dimorphic fungus Paracoccidioides brasiliensis. Its major antigen is a 43 kDa glycoprotein whose peptides embody different functions: P10 peptide, a T-cell epitope, induces protective response while P4 and P23 peptides inhibit both, macrophage functions and inflammatory reaction, thus facilitating infection. Here we investigated the modulating mechanisms of the immune response exerted by P4 and P23 involved in the latter inhibitory effect on macrophages. Moreover we analyzed the peptides effects in different models in vivo. While evaluating whether P4 and P23 present systemic anti-inflammatory effects in vivo, we showed that their intraperitonial administration decreased footpad swelling in mice infected with either P. brasiliensis or Mycobacterium bovis. Both, qPCR and ELISA assays suggested that this anti-inflammatory effect depended on alterations in the kinetics of production of innate immunity modulators such as TNF-α, IL6, IL10 and TLR2. IL10 seems to be early produced than TNF-α and IL6, produced later in presence of peptides. Higher doses or intravenously given P4 and P23 resulted in earlier and more prolonged anti-inflammatory effects. Moreover, continuous treatment with P4 and P23 sustained the anti-inflammatory activity throughout.