Limiting dilution analysis of CD4 T-cell cytokine production in mice administered native versus polymerized ovalbumin: directed induction of T-helper type-1-like activation.

Polarized expression of T-helper type-1 (Th1)- or Th2-like patterns of cytokine production frequently correlates with disease outcome. Previously, we have described the long-lived reciprocal regulation of ovalbumin (OVA)-specific IgE (> 95% inhibition) and IgG2a (300-800-fold increased) production following administration of high MW OVA polymers (OVA-POL), in both de novo and ongoing OVA (alum)-induced responses. Here, limiting dilution analysis (LDA) was used to compare precursor frequencies of CD4 T cells producing interferon-gamma (IFN-gamma), interleukin-4 (IL-4) or IL-10 following OVA versus OVA-POL exposure in vivo. Adjuvants were not used, so as to circumvent their impact on measurement of precursor frequencies. We found that the two forms of antigen elicited T-cell activation of comparable intensity, as indicated by equivalent precursor frequencies of clonogenic antigen-specific CD4 T cells. However, they elicited qualitatively different cytokine responses. OVA-POL treatment led to 10-fold higher (mean of six independent LDA experiments) frequencies of IFN-gamma-producing cells, and a mean fivefold lower frequency of IL-10-producing cells, than was observed following in vivo administration of unmodified OVA. Thus, the high MW polymerized form of antigen acted to steer commitment of naive (for this antigen) CD4 T-cell activation from a situation in which IL-10 producers outnumbered IFN-gamma-producing cells by a factor of 4:1 (found in mice administered OVA), to one where IFN-gamma producers dominated by a factor of 11:1 (in mice given OVA-POL), i.e. a qualitative shift in the nature of the OVA-specific response induced from Th2-like to Th1-like. In vivo co-administration of anti-IFN-gamma monoclonal antibody (mAb) abolished the capacity of OVA-POL to preferentially elicit Th1-like dominance. Interestingly, although the ratios of IFN-gamma:IL-4 and IFN-gamma:IL-10 OVA-specific precursor frequencies were strongly increased following OVA-POL exposure (mean 18- and 47-fold higher), the frequency of IL-4-producing CD4 T cells did not differ significantly. The data suggest that this modified antigen promotes in vivo commitment of naive T cells towards a Th1-like response, with consequent inhibition of IgE and enhancement of IgG2a responses, not through direct effects on IL-4 production, but via decreased frequencies of IL-10 and increased frequencies of IFN-gamma-producing OVA-specific CD4 cells. Collectively, the data (1) demonstrate the ability to manipulate commitment of antigen-driven CD4 T-cell populations in naive mice to specific patterns of cytokine gene expression, and (2) provide in vivo evidence of the regulatory role played by IFN-gamma in limiting induction and/or expansion of IL-4- and IL-10-producing CD4 cells to protein allergens.     

Local breast cancer recurrence after mastectomy and immediate breast reconstruction for invasive cancer: a meta-analysis

BackgroundThe main priorities in the surgical treatment of patients with breast cancer are to achieve cure, local control and prevent recurrence. It is increasingly important to address quality of life and self-image with women undergoing surgical intervention for breast cancer. There is a lack of consensus as to the oncologic safety of immediate breast reconstruction (IBR). The purpose of this paper is to systematically review the literature and compare the frequency of recurrence in patients with and without IBR following mastectomy for breast cancer.MethodsTwo independent investigators searched PubMed, Embase, and the Cochrane database using predefined search terms. After application of inclusion and exclusion criteria, 10 articles remained. Each article was assessed for quality. Relevant data was collected including recurrence rates, cancer stage, type of mastectomy and reconstruction, adjuvant treatments, and duration of follow-up.ResultsInter-rater reliability was good at 74% (95% CI: 0, 93%). There was no evidence of study heterogeneity (p for Q-statistic = 0.34 and I² = 12%). The OR ratio for recurrence of breast cancer for mastectomy with IBR as compared to mastectomy alone was 0.98 (95% CI: 0.62, 1.54).ConclusionThis meta-analysis demonstrated no evidence for increased frequency of local breast cancer recurrence with IBR compared with mastectomy alone     

Differential production of IL-12 in BALB/c and DBA/2 mice controls IL-4 versus IFN-{gamma} synthesis in primed CD4 lymphocytes

The profile of cytokines produced by CD4 T cells is profoundlyinfluenced by the presence of IL-12. Here we demonstrate thatduring re-stimulation of antigen-specific immune responses invitro, antigen-primed lymph node cells from DBA/2 mice produced3- to 30-fold more IL-12 than did cells from BALB/c mice, whichare identical at the major histocompatibility locus. The straindifferences in IL-12 production were observed only in antigen-drivenresponses (and not in responses induced by bacterial products),and were dependent upon an interaction between CD4 T cells andlymph node adherent cells. In addition, differences in the quantityof IL-12 produced by DBA/2 and BALB/c antigen-presenting cells(APC) was not dependent on differential production of IFN- byT cells, since APC from DBA/2 mice still produced much greaterquantities of IL-12 than did BALB/c APC when each was culturedwith the same H-2^d-restricted T_h2 clones, in the complete absenceof IFN, or when each was cultured with primed (BALB/c x DBA/2)F₁T cells. The level of IL-12 produced in the cultures criticallyaffected cytokine production in CD4 T cells, since neutralizationof endogenous IL-12 in DBA/2 cultures, which are predisposedtowards developing T_h1 responses, reduced IFN- production andenhanced IL-4 synthesis to levels normally seen in BALB/c cultures,which are predisposed toward developing Th2 responses. We proposetherefore that differential production of antigen-driven IL-12is a mechanism by which the genetic background in DBA/2 andBALB/c mice can affect the pattern of cytokine synthesis byT cells during the development of adaptive immune responses.     

Long-lived reciprocal regulation of antigen-specific IgE and IgG2a responses in mice treated with glutaraldehyde-polymerized ovalbumin.

Previously, we discovered that administration of high Mr glutaraldehyde-polymerized ovalbumin (OA) to C57BL/6 mice prior to immunization with OA in A1(OH)3 adjuvant resulted in induction of an interferon-gamma (IFN-gamma) dependent, split tolerance in which maximal OA-specific IgE responses were 1-3% of those observed in saline-treated OA-[A1(OH)3] immunized controls. Concomitantly, these mice exhibited up to 10(3)-fold increases in OA-specific IgG2a synthesis. In this report we examine the longevity and resilience of these reciprocal effects on IgE inhibition/IgG2a enhancement over extended periods of time and following multiple re-exposures to the sensitizing allergen. The data indicate that the T-cell mediated changes in responsiveness which are induced upon exposure to glutaraldehyde-modified protein allergen, but not unmodified allergen, are (i) extremely long-lived (greater than 350 days); (ii) resistant to at least five re-immunizations with OA in A1(OH)3 adjuvant; and (iii) antigen-specific. The results are consistent with a virtually permanent shift in the OA-specific T-cell repertoire in vivo from one dominated by Th2-like patterns of cytokine synthesis (IL-4) to one dominated by Th1-like (IFN-gamma) cytokine production.