Search PubMed⌕ Search

Biomedical subjects

H Kiyono

Publications and source records attributed to H Kiyono.

At least 127 records · Page 7Linked to original sources
PubMed1996

Interleukin-12 alters helper T-cell subsets and antibody profiles induced by the mucosal adjuvant cholera toxin.

We have shown that systemic administration of rmIL-12 could trigger Th1-type responses to a protein antigen delivered orally with CT as mucosal adjuvant. The most striking finding was that IL-12 could retain its regulatory effects when orally administered and could redirect the immune response to the oral vaccine toward a Th1-type. However, regulation by orally administered IL-12 differed from parenteral treatment with IL-12 since only the latter treatment affected mucosal S-IgA responses. These findings have important implications for the development of mucosal vaccines that induce the desired immune response.

Adjuvants, Immunologic↗
PubMed1996

Hapten-induced model of murine inflammatory bowel disease: mucosa immune responses and protection by tolerance.

We report here a murine model for experimental chronic colitis where administration of trinitrobenzene sulfonic acid (TNBS) in 50% ethanol induced inflammation of large intestine in susceptible (C3H/HeJ and BALB/c) but not resistant (C57BL/6 and DBA/2) mouse strains. We queried whether mucosal trinitrophenyl (TNP)-specific B cell responses were induced in mice with TNBS-induced colitis, and if induction of tolerance to TNBS by oral administration of this hapten protected mice from development of colitis. Isotypes and subclasses of polyclonal and TNP-specific Ab-forming cells (AFC) were assessed in mucosal and peripheral lymphoid tissues of C3H/HeJ mice with TNBS-induced colitis. Increased numbers of IgA- and IgG-secreting cells were found in the inflamed colon lamina propria. Inflamed colonic tissue also contained high frequencies of IgG anti-TNP AFC (predominantly of IgG1, IgG2a, and IgG2b subclasses); however, anti-TNP responses in noninflamed mucosal tissues of mice with colitis exhibited dominant IgA and IgM with low IgG anti-TNP responses. CD4+ T cells stimulated with TNP-splenocytes produced more IFN-gamma and less IL-4, suggesting a Th1-type response. Oral administration of TNBS before induction of colitis markedly decreased mucosal anti-TNP responses and completely inhibited anti-TNP IgG2a and IgG2b responses. Control mice did not show inhibition of anti-TNP AFC responses or TNBS-induced colitis. Intracolonic sensitization of susceptible C3H/HeJ mice with TNBS induces a localized IgG anti-TNP B cell response in the inflamed tissue, whereas prior oral administration of TNBS results in unresponsiveness to this agent and protects mice from development of TNBS-induced colitis.

Administration, Oral↗
PubMed1996

Luminometry: a novel bioluminescent immunoassay enhances the quantitation of mucosal and systemic antibody responses.

We have directly compared enzyme-linked immunoassays (ELISAs) with bioluminescent immunoassays employing derivatives of the bioluminescent molecule aequorin, and have shown that detection of mucosal and serum antibodies is considerably more sensitive when detected by luminometry. Luminometry is based upon counting photons of light via phototubes and is generally similar to scintillation spectrometry. Current commercial luminometric technology employs a phototube which is most efficient for light emission in the 400-420 nm wavelength range. For this reason, we have chosen the bioluminescent molecule, aequorin, which upon the addition of Ca2+ undergoes a conformational change resulting in the emission of blue light at 469 nm. The high quantum yield is reflected by the fact that addition of Ca2+ to 1 ng of recombinant streptaequorin, a covalent conjugate of streptavidin and aequorin, resulted in the production of 7 x 10(8) relative light units. In this study, we show the superior sensitivity of biotin-streptaequorin when directly compared with biotin-streptavidin linked horseradish peroxidase commonly used for ELISA. For example, mice orally immunized once with cholera toxin (CT) did not exhibit detectable fecal IgA antibodies as determined by ELISA, whereas use of streptaequorin and the bioluminescent immunoassay revealed fecal IgA anti-CT-B subunit antibody titers of 1:24 500. In addition, no detectable anti-CT-B antibodies were noted in saliva samples by ELISA 7 days following oral immunization with CT, while IgA endpoint titers could be extrapolated to 1:393 000. The 21 day fecal IgA anti-CT-B titers were 1:512 by ELISA, whereas titers determined by luminometry reached 1:10(7) when Neutralite avidin and biotinylated aequorin were employed. In general, the bioluminescent immunoassay was > 10(4)-fold more sensitive when compared with ELISA for detection of mucosal and serum antigen- and isotype-specific antibody responses. Thus, the bioluminescent immunoassay is a more sensitive assay for detection of antibodies in dilute external secretions.

Administration, Oral↗
PubMed1996

Interleukin 2 (IL-2) and interleukin 7 (IL-7) reciprocally induce IL-7 and IL-2 receptors on gamma delta T-cell receptor-positive intraepithelial lymphocytes.

In this study, we describe the interaction between cytokine and cytokine receptor (R) for the activation and proliferation of gamma delta T-cell receptor-positive T cells (gamma delta T cells). gamma delta T cells isolated from murine intestinal intraepithelial lymphocytes (IELs) were separated into gamma delta (Dim) and gamma delta (Bright) fractions according to the intensity of gamma delta T-cell receptor expression. The gamma delta T cells express low levels of IL-2R and IL-7R as shown by flow cytometry and reverse transcriptase-PCR analysis, whereas gamma delta (Bright) T cells did not express either receptor. Our study also revealed that recombinant marine (rm)IL-2 and rmIL-7 reciprocally induced high expressions of IL-7R and IL-2R, respectively, on gamma delta (Dim) T cells but not on gamma delta (Bright) cells. Thus, treatment of gamma delta (Dim) T cells with rmIL-2 and rmIL-7 resulted in high proliferative responses, whereas gamma delta (Bright) T cells did not respond to these two cytokines. The sources of these two cytokines for gamma delta T cells were neighboring epithelial cells (IL-7) and alpha beta T cells (IL-2 and IL-7). Cytokine signaling by IL-2 and IL-7 from alpha beta T cells and epithelial cells was necessary for the expression of IL-7R and IL-2R, respectively, on a subset of gamma delta T cells (e.g., gamma delta (Dim) T cells) in mucosa-associated tissue for subsequent activation and cell division.

Animals↗
PubMed1996

gamma/delta T cell-deficient mice have impaired mucosal immunoglobulin A responses.

Mucosal tissues of mice are enriched in T cells that express the gamma/delta T cell receptor. Since the function of these cells remains unclear, we have compared mucosal immune responses in gamma/delta T cell receptor-deficient (TCRdelta-/-) mice versus control mice of the same genetic background. The frequency of intestinal immunoglobulin (Ig) A plasma cells as well as IgA levels in serum, bile, saliva, and fecal samples were markedly reduced in TCRdelta-/- mice. The TCRdelta-/- mice produced much lower levels of IgA antibodies when immunized orally with a vaccine of tetanus toxoid plus cholera toxin as adjuvant. Conversely, the antigen-specific IgM and IgG antibody responses were comparable to orally immunized control mice. Direct assessment of the cells forming antibodies against the tetanus toxoid and cholera toxin antigens indicated that significantly lower numbers of IgA antibody-producing cells were present in the intestinal lamina propria and Peyer's patches of TCRdelta-/- mice compared with the orally immunized control mice. The selective reduction of IgA responses to ingested antigens in the absence of gamma/delta T cells suggests a specialized role for gamma/delta cells in mucosal immunity.

Animals↗
PubMed1996

Regulation of mucosal and systemic antibody responses by T helper cell subsets, macrophages, and derived cytokines following oral immunization with live recombinant Salmonella.

We have assessed regulatory Th cell and cytokine responses in mice after oral immunization with recombinant Salmonella (BRD 847) expressing fragment C of tetanus toxoid, since little information is available to explain how these vectors induce mucosal IgA responses. A single dose of BRD 847 elicited serum IgG2a and mucosal IgA anti-tetanus toxoid Ab responses. To assess Th1-and Th2-type responses, CD4+ T cells from Peyer's patches and spleen were restimulated in vitro, and cytokine-specific ELISPOT, ELISA, and reverse transcriptase-PCR assays were used to assess cytokine patterns. CD4+ T cells produced IFN-gamma and IL-2 as well as IL-10, but not IL-4 or IL-5. Although IL-6 was elevated, further purification of cells from in vitro cultures into CD4+ Mac-1- T cells and Mac-1+ CD4- cells revealed that only the latter cell population had consistently elevated IL-6 gene expression, whereas both sorted populations exhibited increased IFN-gamma and IL-10 gene expression. Thus, orally administered recombinant Salmonella expressing fragment C of tetanus toxoid elicited dominant Ag-specific Th1-type responses together with Th2-type cells producing IL-10 in both mucosal and systemic tissues. Macrophages producing IL-6 were also evident. Our results are consistent with the suggestion that Ag-specific Th1 cells and their derived cytokines, IFN-gamma and IL-2, and Th2-derived IL-10 together with IL-6 produced by macrophages provide important signals for the development of mucosal IgA and serum IgG subclass responses in the absence of preferential expression of Th2 cytokines IL-4 and IL-5.

Administration, Oral↗
PubMed1996

Role of gamma delta T cells in the regulation of mucosal IgA response and oral tolerance.

In this short review, we first described experiments that show that prolonged oral immunization with a protein vaccine, such as DT, induced systemic unresponsiveness in the presence of antigen-specific mucosal IgA responses. Mucosal T cells, such as IEL, may play an important role for the maintenance of antigen-specific IgA responses because these T cells are able to respond to stimulation signals provided by antigen even when T-cell unresponsiveness was induced in systemic tissue, such as spleen of mice orally tolerized with the protein DT. Inasmuch as IEL contain a high frequency of gamma delta T cells, it was logical to postulate that mucosal gamma delta T cells are essential regulatory T cells for the induction of IgA responses in oral tolerance. To this end, our previous studies showed that adoptive transfer of mucosal gamma delta T cells from IEL of mice orally tolerized with SRBC to the recipient mice with systemic unresponsiveness to the same antigen resulted in the abrogation of unresponsiveness to Ig synthesis, including those of IgA isotype. In this regard, when the mucosal immune system of TCR-delta-/- and their control mice was examined, lower numbers of IgA antibody-producing cells were noted in TCR-delta-/- mice in comparison to control background mice. Further, the level of IgA in fecal extracts was also low in TCR-delta-/- mice. These findings suggested that loss of gamma delta T cells in down-regulation of IgA B-cell responses.

Administration, Oral↗
PubMed1996

The role of Th1 and Th2 cells for mucosal IgA responses.

We have used cytokine-knockout mice to help determine the precise requirements for CD4+ Th cell regulation of IgA responses. In these studies, we have used two different oral delivery systems to induce mucosal and systemic antibody responses to the vaccine TT. In normal mice, oral administration of TT with CT as adjuvant induces Th2 cells and cytokines, which give rise to mucosal IgA and serum IgG1, IgA, and IgE responses. On the other hand, oral immunization with rSalmonella expressing Tox C results in Th1-type responses as well as Th2 cell-derived IL-10 and macrophage-derived IL-6, which correlate with mucosal IgA and serum IgG2a antibody responses. Two major conclusions can be drawn from our studies with these two regimens in normal, IFN-gamma-/-, and IL-4-/- mice. First, oral administration of rSalmonella, which elicits classical Th1-type responses also induces significant mucosal IgA responses when given to mice with defective Th1- (IFN-gamma-/-) or Th2- (IL-4-/-) cytokine pathways. Interestingly, we detect Th2-type cells producing IL-10 and macrophage-secreting IL-6 in both normal and cytokine-deficient mice, and we postulate that these two cytokines are of most importance for murine IgA responses. Second, oral administration of TT plus CT as adjuvant induces classical Th2-type responses in both normal and IFN-gamma-/- mice. Further, lack of IL-4 results in failure to induce mucosal IgA responses. Thus, the IL-4 pathway is necessary for the CT adjuvant effect for mucosal IgA responses after oral immunization with a protein vaccine.

Administration, Oral↗
PubMed1996

Mucosal immunity: regulation by helper T cells and a novel method for detection.

The mechanisms which regulate mucosal IgA responses to orally administered protein vaccines are not yet fully elucidated. We have used two delivery systems, soluble tetanus toxoid (TT) with the mucosal adjuvant cholera toxin (CT) and recombinant Salmonella expressing Tox C, a fragment of TT, to assess the nature of CD4+ T helper (Th) cells and derived cytokines which support mucosal IgA responses in both normal and cytokine knockout (interferon gamma knockout; IFN-gamma-/- and IL-4-/-) mice. Our results provide important new information regarding Th cell and cytokine regulation of mucosal IgA responses. Whereas TT coadministered with CT induces predominant TT-specific Th2-type responses, rSalmonella delivery of Tox C induced dominant Th1-type responses along with synthesis of the Th2-cytokine IL-10. Both vaccine regimen elicited high levels of mucosal S-IgA and IL-6 production by macrophages. Further oral immunization of IFN-gamma-/- and IL-4-/- mice with rSalmonella Tox C also induced macrophage-derived IL-6 and Th2-derived IL-10 as well as S-IgA responses, suggesting that IFN-gamma from Th1-type cells as well as traditional Th2 cells producing IL-4 and IL-5 are not essential for mucosal IgA responses. Rather, induction of second level Th2 cells producing IL-10 together with high levels of IL-6 from other cell sources may be sufficient for mucosal IgA responses in the absence of traditional Th2 cells. These studies were facilitated by the development of a sensitive new luminometry assay which allowed detection of cytokines and cell surface molecules which are below the levels of detection by current solid phase assays.

Administration, Oral↗
PubMed1996

Soluble FcR block suppressor T cell activity at low concentration in vitro allowing isotype-specific antibody production.

IgA and IgG binding factors (BF) can be found in the supernatant (Th sup) of cultures containing macrophages and CD4+ T cells stimulated with particulate antigens such as SRBC. Previous work indicated that these IgBF, when mixed with normal serum immunoglobulin, could block the activity of suppressor T cells (Ts) and allow IgA and IgG PFC responses in vitro. We present serologic and functional evidence that IgABF and IgGBF in Th sup are soluble Fc alpha R and Fc gamma RII (or III), respectively. Th sup adsorbed on affinity columns containing anti-Fc gamma RII/III mAB or murine IgG failed to augment IgG PFC responses. Material eluted from either the IgG or anti-Fc gamma RII/III columns could be added back, interchangeably, to the adsorbed Th sup and restore IgG PFC. Recombinant murine Fc gamma RII(rFc gamma RII), added to the same adsorbed Th sup at 0.01 to 0.5 ng/ml, resulted in a similar augmentation of IgG PFC. Interestingly, much higher concentrations of rFc gamma RII (10-100 ng/mL) could not augment IgG PFC responses. Protein dot blots showed that Th sup and the eluted material from murine IgG columns contained structures reactive with the Fc gamma RII/III mAb. Similar studies using purified Fc alpha R revealed that IgABF eluted from IgA or anti-Fc alpha R revealed that IgABF eluted from IgA or anti-Fc alpha R columns was in fact Fc alpha R. Cross-adsorption studies indicated clearly that the IgGBF (Fc gamma RII/III) and the IgABF (Fc alpha R) were separate molecules produced in the same Th sup and that each regulated their respective Ig isotype independently. Thus, cultures of splenic macrophage and CD4+ T cells, in the presence of particulate antigens such as SRBC, generate both Fc gamma RII/III and Fc alpha R. This soluble FcR in combination with serum Ig act to block isotype specific Ts cells at low concentration in vitro.

Animals↗
PubMed1996

Induction of pneumococcal polysaccharide-specific mucosal immune responses by oral immunization.

Liposome and cholera toxin (CT) are considered to be effective antigen delivery vehicles and adjuvants for mucosal vaccines. The effect of these antigen delivery systems on adjuvant responses to mucosally administered pneumococcal polysaccharide (Pnup) was investigated in this study. Both mucosal (e.g. oral) and systemic (i.p.) immunization of mice with purified preparations of Pnup type 23F induced antigen-specific IgM responses in sera. Interestingly, oral immunization of as little as 10 micrograms of Pnup type 23F was sufficient to induce systemic IgM responses. Pnup-specific IgM antibodies peaked by day 7 and no booster responses were evident after a second dose on day 14. In order to examine whether IgG and IgA Pnup-specific immune responses are induced by mucosal immunization, the mucosal adjuvant CT was mixed with Pnup type 23 as an oral vaccine. Co-oral administration of CT and Pnup type 23F resulted in the induction of Pnup-specific faecal IgA antibodies. These results were confirmed by detecting antigen-specific IgA-spot-forming cells in mononuclear cell suspensions prepared from the intestine of immunized mice. These findings suggest that oral immunization with Pnup in the presence of mucosal adjuvants, such as CT, could induce Pnup-specific IgA responses whereas Pnup alone did not. In an attempt to further enhance antigen-specific antibody responses, Pnup type 23F was encapsulated in liposomes and used as mucosal vaccine. However, immunogenicity of Pnup was not improved.

Administration, Oral↗
PubMed1996

Mechanisms for mucosal immunogenicity and adjuvancy of Escherichia coli labile enterotoxin.

Escherichia coli labile toxin (LT) was assessed as mucosal immunogen and as adjuvant for tetanus toxoid (TT) in mice. After oral administration of LT, C57BL/6 (H-2b) and BALB/c(H-2d) mice were high mucosal and serum antibody responders, while C3H/HeN (H-2k) mice were low responders. High responders exhibited mainly serum IgG (including IgG1, IgG2a, and IgG2b), as well as IgM and IgA, while mucosal responses were IgA. Analysis of LT-B-specific CD4+ T helper (Th) cells from Peyer's patches (PP) or from spleen revealed a mixed Th1 (interferon-gamma) and Th2 (interleukin-4 and -5) cell pattern. Oral LT given with TT induced TT-specific response patterns identical to LT-B. Analysis of mRNA from TT-specific PP CD4+ Th cells also revealed a mixed Th1- and Th2- type response. Thus, antibody response profiles induced by LT are regulated by both CD4+ Th1 and Th2 cell types.

Adjuvants, Immunologic↗
PubMed1996

Oral immunization with the B subunit of the heat-labile enterotoxin of Escherichia coli induces early Th1 and late Th2 cytokine expression in Peyer's patches.

The B subunit of heat-labile toxin (LT-B) from enterotoxigenic Escherichia coli has been shown to be a powerful mucosal immunogen. Oral immunization of mice with LT-B revealed that BALB/c (H-2d) and C57BL/6 (H-2b) mice gave high serum IgG and mucosal IgA responses specific for LT-B. However, ALY (H-2b) mice lacking intestinal Peyer's patches (PP) did not respond to oral LT-B with either serum or mucosal antibodies. These results indicate that PP lymphocytes supported both systemic and mucosal immune responses when the antigen was administered orally. Reverse transcription polymerase chain reaction analyses revealed that PP CD4 T cells expressed early Th1-type (interferon-gamma and interleukin [IL]-2) and late Th2-type (IL-4, -5, and -6) cytokine mRNA. These results suggest that the systemic and mucosal antibody responses induced by LT-B are regulated by a cooperation of PP Th1 and Th2 cells.

Animals↗
PubMed1996

Selected Th1 and Th2 cytokine mRNA expression by CD4(+) T cells isolated from inflamed human gingival tissues.

Elevated numbers of plasma cells are associated with localized and chronically inflamed gingiva of patients with adult periodontitis. However, only limited information is currently available as to how cytokines produced by CD4(+) T cells are involved in these increased B cell responses in affected gingival tissues. When gingival mononuclear cells (GMC) were isolated from inflamed tissues and examined by flow cytometry, approximately 20-30% of lymphocytes were CD4(+) T cells. For the analysis of Th1 and Th2 cytokine expression by these CD4(+) T cells, RNA was extracted and reverse transcriptase-polymerase chain reaction (RT-PCR) was performed by using specific 5' and 3' primers for interferon-gamma (IFN-gamma) and IL-2 (Th1), IL-4, IL-5, IL-6, IL-10 and IL-13 (Th2) and beta-actin (internal control). Two distinct cytokine profiles were noted based on the expression of selected Th1 and Th2 cytokines, where one pattern was represented by expression of mRNA for IFN-gamma, IL-6, IL-10 and IL-13, while the second consisted of mRNA for IFN-gamma, IL-6 and IL-13. In most samples, mRNA for IL-2, IL-4 and IL-5 were not detected by cytokine-specific RT-PCR. When RNA was isolated from CD4(+) T cells of concanavalin A-stimulated peripheral blood mononuclear cells (PBMC) of the same patients and examined by RT-PCR, mRNA for all Th1 and Th2 cytokines were detected. These findings suggest that although human CD4(+) T cells are capable of producing an array of Th1- and Th2-type cytokines, the CD4(+) T cells associated with periodontitis are limited to production of IFN-gamma, IL-6, IL-13 and is some instances IL-10. CD4(+) T cells from diseased periodontal tissues are divisible into two groups based upon whether or not IL-10 is produced, together with IFN-gamma, IL-6 and IL-13.

Adult↗
PubMed1996

Epitope maps of the Escherichia coli heat-labile toxin B subunit for development of a synthetic oral vaccine.

Linear B- and T-cell epitopes spanning all 103 amino acids of the Escherichia coli heat-labile toxin B subunit (LT-B) were assessed in mice orally immunized with native LT or with recombinant Salmonella enteritidis expressing LT-B. Oral administration of native LT induced mucosal immunoglobulin A (IgA) antibodies reactive with an epitope at residues 85 to 91, while IgA induced by recombinant Salmonella LT-B reacted with an epitope at residues 36 to 44. Serum IgG anti-LT-B antibodies from mice orally immunized with either LT or with recombinant Salmonella LT-B were directed to both epitopes. A single T-cell epitope spanning residues 34 to 42 was identified by T-cell proliferative and cytokine responses. When a 20-mer peptide (residues 26 to 45) with B- and T-cell epitopes was given orally to BALB/c (H-2(d)) and B10 congenic (I-A(d), I-A(b), and I-A(k)) mice, significant fecal IgA and serum IgG anti-LT-B antibodies were induced. The peptide also induced LT-B-specific T-cell proliferative responses in these mice. Orally administered LT-B peptide (residues 26 to 45) induced a cytokine profile indicative of both T helper 1- and 2-type cells. The remarkable immunogenicity of this 20-mer peptide makes it a candidate for a vaccine to protect against enterotoxigenic E. coli.

Administration, Oral↗
PubMed1996

Oral immunization of interleukin-4 (IL-4) knockout mice with a recombinant Salmonella strain or cholera toxin reveals that CD4+ Th2 cells producing IL-6 and IL-10 are associated with mucosal immunoglobulin A responses.

Mucosal immunoglobulin A (IgA) responses are often associated with Th2-type cells and derived cytokines, and interleukin-4 (IL-4) knockout (IL-4-/-) mice with impaired Th2 cells respond poorly to oral antigens. However, we have noted that IL-4-/- mice have normal mucosal IgA levels, which led us to query whether different oral delivery systems could elicit mucosal immunity. Two oral regimens were used: (i) a live recombinant Salmonella strain which expresses fragment C (ToxC) of tetanus toxin, and (ii) soluble tetanus toxoid (TT) with cholera toxin (CT) as an adjuvant. Oral immunization of IL-4-/- mice with recombinant Salmonella vaccine expressing ToxC induced brisk mucosal IgA and serum IgG (mainly IgG2a) anti-TT antibody responses. TT-specific CD4+ T cells from spleen or Peyer's patches produced gamma interferon, indicative of Th1 responses; however, IL-6 and IL-10 were also seen. Oral immunization of IL-4-/- mice with TT and CT induced weak mucosal IgA to TT; however, brisk IgA anti-CT-B responses and CT-B-specific CD4+ T cells producing IL-6 and IL-10 were also noted. These results show that although IL-4-dependent antibody responses are impaired, mucosal IgA responses are induced in IL-4-/- mice. These result suggest that certain cytokines, i.e., IL-6 and IL-10 from Th2-type cells, play an important compensatory role in the induction and regulation of mucosal IgA responses.

Adjuvants, Immunologic↗
PubMed1996

Absence of exogenous interleukin-4-induced apoptosis of gingival macrophages may contribute to chronic inflammation in periodontal diseases.

Inflamed gingival tissues are enriched in macrophages (MOs) and CD4-positive T cells; however, T helper-type cytokines such as interleukin (IL)-2 and IL-4 are absent. Therefore, we investigated whether a relationship exists between IL-4 receptor (IL-4R) expression and MO persistence in the absence of exogenous IL-4. Gingival MOs, when compared with monocyte(MN)/MOs from peripheral blood mononuclear cells, expressed high levels of IL-4R mRNA. Furthermore, in vitro cultures of gingival MOs remained viable whereas identically treated peripheral blood MN/MOs rapidly lost viability. However, when gingival MOs were incubated with recombinant IL-4 (rIL-4), the cell viability was dramatically reduced. When the frequency of apoptotic cells was assessed in rIL-4-treated gingival MO cultures, higher numbers of apoptotic cells were noted in rIL-4-treated versus control cultures. Furthermore, rIL-4-treated MOs from inflamed gingiva showed DNA fragmentation as assessed by electrophoresis. These findings clearly show that addition of exogenous rIL-4 to gingival MO cultures leads to cell death by apoptosis. This finding would suggest that topical application of rIL-4 may inhibit the persistence of MOs in adult periodontitis, which could then lead to decreased inflammation.

Adult↗