Role of 57 kDa major antigenic component of Shigella dysenteriae outer membrane proteins in induction of major histocompatibility complex II-restricted T-cell response.
BACKGROUND
In the past, many Shigella surface antigens were used to activate both T and B lymphocytes but failed to induce antigen-specific responses in Shigellosis. Our objective was to identify in vitro T-cell components using 57 kDa major antigenic fraction of Shigella dysenteriae 1 (IPC-31) outer membrane proteins (OMPs) in modulating specific T-cell subset responses against Shigellosis.


METHODS
Antigen-specific T- and B-cell activation was studied in immunized Balb/c mice against 57 kDa antigen by proliferative responses using [3H]-thymidine incorporation and avidin-biotin complex (ABC) peroxidase staining for CD4, CD8, CD3, CD22, and CD25 followed by IL-2 and IL-4 estimation. Macrophage functional assays for migration inhibition factors (MIF) and superoxide (O2-) anions were also performed against 57 kDa antigen, whole OMPs, and phytohemagglutinin (PHA) stimulation.


RESULTS
Greater increase of lymphocyte proliferation was observed after 57 kDa antigen stimulation than post-OMP and -PHA stimulation. Proportionately, CD4+ and CD25+ expression of total CD3+ T-cells was significantly dominant (p >0.05) over CD8+ T-cells. On day 7 of this stimulation, it was found to increase % MIF and O2- anions with decrease of IL-2 leading to activation of MHC-II antigens. Later, on day 28 of immunization, IL-2 levels were more increased than on days 7 and 14 but insignificant with non-immunized mice stimulated with 57 kDa. Levels of IL-2 were also noted with low degree of internalization to its IL-2R receptors rather than to IL-4 receptors. In parallel, expression of CD22 was also recorded higher in this stimulation than in PHA, indicating a T-cell-dependent humoral response.


CONCLUSIONS
Our results suggested that 57 kDa major antigenic OMP is immunogenic for MHC II-restricted T-cell response to acquire host defense against Shigella infection.
Bagchi
Ashim K
AK
Division of Immunology and Vaccine Development, National Institute of Cholera & Enteric Diseases, Kolkata, India.
Sinha
Ajoy K
AK
D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007376:Interleukin-2 / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology; D008285:Major Histocompatibility Complex / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D012762:Shigella dysenteriae / Q000276:immunology*; D013481:Superoxides / Q000378:metabolism; D016176:T-Lymphocyte Subsets; D013601:T-Lymphocytes / Q000276:immunology*
D015703:Antigens, CD; D001425:Bacterial Outer Membrane Proteins; D000949:Histocompatibility Antigens Class II; D007376:Interleukin-2; D013481:Superoxides; D015847:Interleukin-4