Effects of anti-immunoglobulin antibodies on murine B lymphocytes and humoral immune responses

Neutrophil-to-Lymphocyte Ratio Positively Correlates to Age in Healthy Population

BACKGROUND

Neutrophil to lymphocyte ratio (NLR) was reported to be an independent easy-to-measure marker for many diseases, while the distribution of NLR in healthy population was not formally studied. So we investigated NLR in healthy people in this study.

METHODS

Data include NLR, systolic pressure, diastolic pressure, and body mass index (BMI), which were collected from 3,262 healthy population. Correlations of NLR with variables were analyzed with SPSS16.0.

RESULTS

Results demonstrated that NLR was positively associated with age (P < 0.001). The eldest age group possessed the highest NLR and the youngest age group had the lowest NLR. NLR was also slightly positively associated with systolic pressure, diastolic pressure, and BMI (P < 0.001).

CONCLUSION

Older people possessed relatively high NLR in healthy population.

TLR-mediated B cell activation results in ectopic CLIP expression that promotes B cell-dependent inflammation

Infectious pathogens produce compounds called Toll ligands that activate TLRs on lymphocytes. Acute activation triggered by certain TLRs appears to "jump start" the innate immune response, characterized by the release of inflammatory cytokines and cellular expansion. In some individuals, there is a failure to control acute inflammation, resulting in postinfectious, chronic inflammation. Susceptibility to chronic inflammation is strongly associated with an individual's MHC genes. Recent clinical trials for several autoimmune diseases characterized by chronic inflammation suggest that B lymphocyte depletion therapies dampen chronic immune activation. However, currently, there is no known mechanism that accounts for the correlation among TLR activation, MHC genetics, and a pathological role for B-lymphocytes. Our hypothesis is that TLR-activated B cells (B cells that have been polyclonally activated in the absence of antigen-specific signals) are not controlled properly by T cell-dependent B cell death, thereby causing B cell-dependent chronic inflammation. Here, we show that treatment with Toll ligands results in polyclonal B cell activation accompanied by ectopic expression of CLIP. Furthermore, by adoptively transferring purified CLIP+ B cells in syngeneic animals, we find that CLIP+ B cells induce production of TNF-α by host T cells. Finally, we demonstrate that CLIP-targeted peptide competition results in the death of polyclonally activated CLIP+ B cells.

Differential activation requirements of isotype-switched B cells

In the present studies, we compared the activation requirements of sIgM+/sIgD+ B cells with those of isotype-switched sIgM-/sIgA+ B cells. We found that whereas sIgM+ B cells respond to T cell-independent (TI) and T cell-dependent (TD) Ag with no significant bias toward one stimulus, sIgA+ B cells were deficient in their ability to respond to antigen receptor cross-linking but responded remarkably well to TD stimuli. Thus, dextran-conjugated anti-IgA antibody (anti-IgA-dextran), anti-kappa-dextran, or various immobilized anti-IgA antibodies (Ab) induced only low-level IgA B cell proliferation and no IgA secretion in the presence of various lymphokines; in marked contrast, sIgA+ B cells responded to cognate and noncognate T cell stimulation as well as to stimulation by CD40 ligand-bearing fibroblasts by secreting large amounts of IgA (up to 240 000 ng/ml per 10(5) cells). This pattern of sIgA+ B cell responsiveness was noted with both germinal center peanut agglutininhi (PNAhi) and non-germinal center PNAlo B cells. In confirmation of these results, whole Peyer's patch or lamina propria cell populations containing less than 15% sIgA+ B cells stimulated with a noncognate T cell stimulus or T cell membranes secreted mainly IgA (68%-94% of the total Ig secreted) and relatively little IgM. The strict T cell dependence of IgA B cell activation and differentiation provides important insights into immune responses of mucosal tissues and must be considered in the development of vaccines, particularly those designed to stimulate mucosal tissues containing large numbers of isotype-switched B cells.

Restriction mechanisms of B cell regulation by a physiological IgG-anti-immunoglobulin autoantibody

Immunization of LEW rats with strongly histoincompatible BN blood cells induces, in addition to anti-donor antibody, a broadly reactive IgG autoantibody which binds to IgG and IgM molecules (IgG anti-Ig). Minute amounts of affinity purified IgG anti-Ig (0.2 pg/10(6) cells) suppress the antibody production in vitro of antigen receptor (AgR)-stimulated B cells derived from rats of the same strain. The suppressive antibody is also active in the whole serum IgG fraction. Importantly, anti-Ig-induced suppression is governed by restriction mechanisms: only AgR-occupied B cells are affected, the suppression is cell cycle dependent, and maximum suppression is obtained at an optimum IgG concentration. Treatment of rats in vivo with 0.8 mg Ig-anti-Ig (whole IgG fraction) along with allogeneic cells resulted in nearly complete suppression of the anti-donor antibody response. Possible mechanisms of B cell suppression by IgG anti-Ig are crosslinking of AgR with FcR, or cocapping of the two receptors with sterical interaction as a consequence of their separate occupation. Both alternatives lead to the release of an inactivating signal.

Long-lasting kidney graft survival after immunization with antibody-coated blood cells: mediation by immunosuppressive autoantibodies

Treatment of LEW rats before transplantation with BN blood cells preincubated with LEW-anti-BN serum resulted in prolonged BN kidney graft survival (untreated, 8 +/- 0.4 days; pretreated, 124 +/- 36). The serum of pretreated animals contains a factor which suppresses T cell proliferation against donor antigens. This effect was not mediated by antiidiotypic antibodies because it was reproduced in a donor-unrelated system. The serum and IgG of pretreated animals also suppressed the humoral immune response. As for T cells, the antibody-suppressive effect was not donor-restricted. A broadly reactive anti-immunoglobulin (anti-B cell) autoantibody was found in the IgG fraction of immunized animals. The mediation of immunosuppression by broadly reactive anti-B and T cell autoantibodies induced by the immunization with antibody-coated blood cells is discussed.

Suppression of specific IgM, IgA and IgG responses in mice treated with anti-delta from birth

In contrast to previous studies, we report that heterologous anti-delta antibodies can act as a powerful multi-class humoral immunosuppressant. Primary direct plaque-forming cell (IgM) responses of BALB/c mice injected from birth with a rabbit anti-delta antiserum were reduced to 3% of control levels against a T-dependent antigen (sheep red blood cells), and to 2% against a T-independent antigen (dextran); IgA responses against 2 intraduodenal injections of cholera toxin were reduced to 7% of control levels. Other secondary immune responses of anti-delta-suppressed mice were suppressed to a lesser degree. IgM plaque responses generated by 2 injections of sheep red cells, for example, were reduced to 50% of control levels, with reduction of the corresponding IgG response to 42%. The multi-class suppression observed indicates a clonal differentiation pathway in which the IgD+ cell develops into IgM-, IgA- and IgG-secreting cells. In light of reports that the IgD+ cell is antigen sensitive, our demonstration that IgD is capable of delivering the same sort of immunosuppressive signal in response to anti-heavy chain antibodies that IgM delivers also suggests, though it does not establish, an antigen-receptor role for IgD.

Cyclic AMP-dependent protein kinase content of murine T and B lymphocytes

Murine splenic lymphocytes have been separated by non-activating procedures into enriched T and B cell populations. Cyclic AMP-dependent protein kinase (cAPK) activity has been measured in those separated cell types by histone phosphorylation. As in other tissues, lymphocyte cAPK activity was found to be predominantly a soluble enzyme. By an analysis of cyclic AMP (cAMP) activation of enzyme activity it was shown that: (1) the basal activities were indistinguishable between these major lymphocyte subpopulations, (2) the Ka values for cAMP activation were identical for the two cell types (24 nM cAMP), and (3) the Vmax for enzyme activity was higher in T (5.47 pmole/min/10(6) cells) than in B (3.58 pmole/min/10(6) cells) cells. DEAE-cellulose chromatography experiments with mixed and enriched splenic lymphocyte populations extended and amplified this quantitative difference between T and B cells.

Cyclic AMP-dependent protein kinase content of murine splenic T and B lymphocytes and non-lymphoid tissues

Cyclic AMP-dependent protein kinase activity has been measured in DEAE-cellulose elution profiles of highly enriched murine splenic T and B Lymphocytes. B Lymphocytes were found to contain about 10% of the amount of enzyme activity associated with T lymphocytes and several non-lymphoid tissues. Cyclic AMP-independent casein kinase activities were equivalent in T and B lymphocytes. Lymphocytes contained predominantly type I isozyme as opposed to several non-lymphoid tissues which all contained predominantly the type II form.