Modulation of suppressor mechanisms in allergic contact dermatitis: 2. Inhibition of suppressor T-lymphocytes by Corynebacterium parvum

Ocular surface inflammation induced by Propionibacterium acnes

PURPOSE

In the eye, is commonly isolated in the lid, conjunctiva, and meibomian gland secretion. Well known as a causative bacterium of granulomatous endophthalmitis and a potent inflammatory stimulus, reportedly induces a delayed-type hypersensitivity (DTH) response and forms granulomas in the liver and lung in animal models. In this study, we examined whether can induce a DTH response in the cornea.

METHODS

Six- to 8-week-old female Lewis rats were immunized with heat-killed suspension of and assessed as to DTH response via ear challenge at 2 weeks after immunization. At 3 weeks after immunization, suspension was injected in the rat corneal stroma, which was then observed biomicroscopically at 6, 24, and 48 hours after injection. Phenol-killed suspension was also used for the comparison. Histological examination was also performed on the corneal tissues, using hematoxylin and eosin staining as well as immunohistochemical staining against CD4 and CD8 T cells.

RESULTS

Rats immunized with suspension showed significantly higher ear swelling values at both the 24- and 48-hour measurements than did the naïve controls (p < 0.005). Massive cellular infiltration with stromal edema was observed biomicroscopically at 48 hours after injection of suspension in the corneal stroma. Histological study showed that the cell infiltration pattern was similar to that of DTH in the skin, i.e., neutrophils infiltrated at 6 hours, followed by mononuclear cells that, including macrophages and lymphocytes, increased and mixed with neutrophils, accompanied by stromal edema at 48 hours. Immunohistochemical study revealed that CD4 T-cell infiltration in the corneal stroma appeared to predominate over CD8 T-cell infiltration.

CONCLUSIONS

These results indicate that can induce a DTH response in the cornea and may be a causative bacterium of ocular surface inflammation.

Immunologic effects of interferon

Interferons can be defined as a family of induced proteins sharing the capacity to exert pleiotropic effects on cell functions and to render cells resistant to virus infection. They are activating genes coding for a number of enzymes, most of which have not yet been characterized, and also by enhancing the synthesis of cell surface components. This enables interferons to modulate the immune response at different levels. This article will focus on the effects of interferon on antigen presentation, regulation of the immune response, activation of macrophage functions, and on its role in the pathogenesis of some diseases.

Inhibitory effects of interferon-gamma on the T suppressor cell circuit in contact sensitivity

The effects of a partially purified, splenocyte-derived murine interferon (MuIFN-gamma N) and a recombinant IFN-gamma (MuIFN-gamma R) on the T suppressor pathway and on the T effector cells of delayed type hypersensitivity were investigated in a 2,4-dinitrofluorobenzene contact sensitivity model. Various T cell subpopulations, suppressor T cells of afferent and efferent types, and an auxiliary T suppressor cells as well as a T effector cell of delayed type hypersensitivity were induced and the functions assessed in transfer experiments. Confirming the results of earlier experiments obtained with IFN-alpha, beta, the MuIFN-gamma N preparation and the rec. MuIFN-gamma R: enhanced the decreased response in animals sensitized with an antigen overload to an optimal response; inhibited the afferent-acting T suppressor cell in vivo and in vitro; inhibited the Ts-eff response; blocked the auxiliary T suppressor cell response after intravenous injection to recipients of Ts-eff cells on day 0 and 1; and did not suppress the activity of the T effector cell of delayed type hypersensitivity in vivo and in vitro (the MuIFN-gamma R was not tested). We conclude that IFN-gamma preferentially inhibited the T suppressor cell circuit of contact allergy. These results are similar to our observations on the inhibitory effects of a pure interferon-alpha, beta on the regulatory T suppressor cell circuit in contact allergy. Selective suppression of different T subpopulations by IFN-gamma may be an important regulatory mechanism in delayed type hypersensitivity.

Selection of the delayed hypersensitivity T effector and T suppressor cell response by antigen-presenting macrophages

The T effector lymphocytes of delayed type hypersensitivity reactions (TDH) are regulated by a complex T suppressor (Ts) cell circuit. Induction of TDH cells requires Ia+ adherent cells as antigen-presenting cells. Little is known about the antigen presentation of the induction of Ts cells. We describe an experimental model in which TDH and Ts cells are induced separately by different antigen-presenting macrophages grown from bone marrow stem cells. Bone marrow derived macrophages grown in L cell-conditioned medium for various periods and labeled with 2,4-dinitrobenzene sulfonic acid differ in their ability to induce TDH and Ts cells in vitro. The functional activity of the two T subpopulations was assessed in vivo by epicutaneous challenge or sensitization with 2,4-dinitrofluorobenzene of mice receiving the in vitro educated cells. Ear swelling or suppression of swelling was recorded. It could be shown that 5-7 day bone marrow-derived DNP-labeled macrophages preferentially induced Thy 1+ Lyt 1+ antigen-specific TDH cells; 7-10 day old antigen-presenting bone marrow-derived macrophages induced preferentially Thy 1+ Lyt 2+ antigen specific Ts cells. Characterization of various phenotypic markers revealed different surface antigen expression and functional differences such as MIF responsiveness or transglutaminase activity on the two macrophage populations. These data support the concept that activation of the Ts regulatory circuit may require antigen presentation by specialized antigen presenting cells, characterized by certain surface and functional markers and different from those inducing preferentially TDH cells.

Modulation of suppressor mechanisms in allergic contact dermatitis: 5. Evidence that inhibition of suppressor T lymphocytes by Corynebacterium parvum is mediated by interferon

Using a contact hypersensitivity model in BALB/c mice we have previously been able to show that Corynebacterium parvum or C. parvum serum (C.p.s.) of mice treated 24 hr before with C. parvum inhibited the suppressor T-lymphocyte (Ts-cell) response induced by epicutaneous antigen overload with 2,4-dinitrofluorobenzene (DNFB) or by i.v. injection of 2,4-dinitrobenzene sulfonic acid (DNBSO3) without inhibition of the T effector cell response (TDH-cell). In the present investigation we further analyzed the factor responsible for Ts-cell inhibition. Treatment of the C.p.s. with sheep-antimouse interferon (IFN) globulin neutralized its Ts-cell inhibitory effect. Intravenous (i.v.) injection of a crude mouse fibroblast IFN (340 U per mouse) 2 hr after i.v. application of a dose of DNBSO3 inducing tolerance had a similar Ts-cell inhibitory effect as observed with C.p.s. Injection of an electrophoretically pure alpha- and beta-IFN preparation (1000 U per mouse) increased contact sensitivity in mice sensitized with an antigen overload and inhibited the induction of Ts-cells by DNBSO3 i.v. This result is highly suggestive that the Ts-cell inhibitory factor in serum of C. parvum-treated mice is IFN and it shows that Ts-cells as compared to TDH-cells are susceptible to the inhibitory effect of highly purified IFN. This finding suggests that IFN may be an important immunoregulatory factor of delayed hypersensitivity not only in contact allergy but also in bacterial and viral defense.