ovalbumin and Burns

Severe injury induces detrimental changes in immune function, often leaving the host highly susceptible to developing life-threatening opportunistic infections. Advances in our understanding of how injury influences host immune responses suggest that injury causes a phenotypic imbalance in the regulation of Th1- and Th2-type immune responses. We report in this study, using a TCR transgenic CD4(+) T cell adoptive transfer approach, that injury skews T cell responses toward increased Th2-type reactivity in vivo without substantially limiting Ag-driven CD4(+) T cell expansion. The increased Th2-type response did not occur unless injured mice were immunized with specific Ag, suggesting that the phenotypic switch is Ag dependent. These findings establish that severe injury induces fundamental changes in the induction of Ag-specific CD4(+) Th cell responses favoring the development of Th2-type immune reactivity in vivo.

Topics: Adoptive Transfer; Amino Acid Sequence; Animals; Antigens; Burns; CD4-Positive T-Lymphocytes; Cell Differentiation; Cell Division; Cytokines; Epitopes, T-Lymphocyte; Immunity, Innate; Male; Mice; Mice, Inbred BALB C; Mice, Transgenic; Molecular Sequence Data; Ovalbumin; Peptide Fragments; Th2 Cells; Up-Regulation

The mechanisms responsible for altered T-cell responses and cytokine production after injury are not well understood. We used T-cell receptor (TCR) transgenic mice to study burn injury effects on naive versus antigen-activated CD4+ T cells in vivo.. One week after sham or burn injury, lymph node cells were prepared from TCR transgenic mice and stimulated with TCR transgene-specific antigens. T-cell proliferation was measured and culture supernatants were tested for interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-4, and IL-10 by enzyme-linked immunosorbent assay (ELISA). Burn injury effects on antigen-activated T cells were studied by immunizing TCR transgenic or wild-type mice at the time of injury.. The antigen-stimulated proliferation of native CD4+ T cells was unaffected by burn injury and no increase in T-helper 2 (Th2)-type cytokine production was observed. Instead, burn injury augmented INF-gamma production by naive CD4+ transgenic T cells, and IL-2 production was marginally reduced. Thus, burn injury primed native T cells for an enhanced Th1-type response. In contrast, antigen-specific proliferation, IL-2, and IFN-gamma production by T cells harvested from immunized wild-type mice were suppressed. Unexpectedly, high mortality was observed when burn-injured TCR transgenic mice were immunized.. Our results show that burn injury has differential effects on naive and antigen-activated CD4+ T cells and can prime naive CD4+ T cells.

Topics: Animals; Antigen Presentation; Antigens; Burns; CD4-Positive T-Lymphocytes; Cell Division; Disease Models, Animal; Interferon-gamma; Interleukin-10; Interleukin-4; Lymphocyte Activation; Male; Mice; Mice, Inbred A; Mice, Transgenic; Ovalbumin

Studies have shown that susceptibility to sepsis after severe injury correlated with reduced production of T-helper 1 (Th1) cytokines (interleukin-2 [IL-2] and interferon-gamma [IFN-gamma]) and a persistence of T-helper 2 (Th2) cytokines (IL-4 and IL-10). The mechanisms responsible for this effect are not clear. We used a T-dependent antigen to study both the effect of burn injury on antigen-specific Th functions in vivo and the effect of anti-IL-10 antibody on these functions.. Male A/J mice were anesthetized and given a 25% scald burn or a sham burn. On day 0 all mice were immunized with 100 micrograms trinitrobenzene sulfonic acid (TNP) haptenated ovalbumin (TNP-OVA) in complete Freund's adjuvant. Mice (10 per group) were given 250 micrograms monoclonal rat antimurine IL-10 antibody (anti-IL-10 MAB) or control rat immunoglobin G (IgG) on day 0 and 100 micrograms anti-IL-10 MAB or IgG on day 2. On day 10 the mice were killed to obtain serum and spleen cells. TNP-specific serum antibody isotype titers were determined by enzyme-linked immunosorbent assay (ELISA). Splenocyte proliferation and cytokine-production in response to TNP-OVA or to anti-CD3 MAB were determined by tritiated thymidine incorporation and by ELISA, respectively.. Burn injury resulted in depressed levels of the TNP-specific IgG2a antibody isotype (Th1 dependent), whereas TNP-specific IgG1 and IgE (Th2 dependent) levels were not decreased in burn versus sham burn mice. Anti-IL-10 MAB but not IgG restored the IgG2a response. Burn injury also resulted in reduced TNP-OVA-specific proliferation of splenocytes, whereas anti-CD3 proliferation was equivalent in burn and sham mice. TNP-OVA-specific IL-2 and IFN-gamma production were significantly reduced by burn injury. Anti-IL-10 MAB restored TNP-OVA-specific proliferation and antigen-specific IL-2 and interferon-gamma production by splenocytes from burn mice.. Burn injury induces the loss of antigen-specific Th1 cell function, and IL-10 acts as a trigger to down-regulate Th1 activity after injury.

Topics: Animals; Antibodies, Monoclonal; Antibody Formation; Burns; Cells, Cultured; Enzyme-Linked Immunosorbent Assay; Freund's Adjuvant; Immunoglobulin E; Immunoglobulin G; Immunoglobulin Isotypes; Interferon-gamma; Interleukin-10; Interleukin-2; Lymph Nodes; Lymphocyte Activation; Male; Mice; Mice, Inbred A; Ovalbumin; Rats; Reference Values; Spleen; T-Lymphocytes; Th1 Cells; Th2 Cells; Trinitrobenzenesulfonic Acid