Lee K. Roberts

Identification and characterization of mononuclear phagocytes isolated from rat testicular interstitial tissues

Rat testicular interstitial tissues contain numerous mononuclear phagocytelike cells. Dispersed testicular tissues are allowed to settle onto a glass substrate and the strongly adherent cells are identified as the same cells that have been described in vivo, based on the retention of an in vivo marker (plutonium). These putative testicular intersitial tissue macrophages (TIMs) have adhesion and cell surface features characteristic of mononuclear phagocytes, as determined by scanning electron microscopy. Immediately after isolation from testicular tissues. TIMs show a strong staining reaction for nonspecific esterase. These cells have Fc and complement receptors and some express la cell‐ surface antigens. About two thirds of the TIMs phagocytose sheep red blood cells and most of the cells are capable of nonspecific phagocytosis of polystyrene beads. This study demonstrates that the phagocytic cells found in testicular interstitial tissues have morphological, histochemical, phagocytic, and immunological properties characteristic of functionally active mononuclear phagocytes. These results suggest that these resident mononuclear phagocytes may play a role in immune‐related functions in the testis.

Evidence for two functionally distinct cross-reactive tumor antigens associated with ultraviolet light and chemically induced tumors.

Experiments were conducted to determine the distribution and function of common tumor antigens shared by ultraviolet light (UV)., benz[a]pyrene (BP)-, and methylcholanthrene (MCA)-induced tumors. When lymph node cells were removed from UV, BP, or MCA tumor-immune mice and held in tissue culture for 4 days, a population of cytotoxic T lymphocytes (CTLs) emerged that were capable of lysing a battery of different tumor targets. In addition to their ability to lyse chromium-labeled tumor cells in vitro, these CTLs displayed cross-reactive in vivo activity in Winn-type assays. Blocking experiments suggested that these CTLs recognized tumor-associated antigens (TAAs) common to both UV and chemically induced tumors. Although these common TAAs were recognized by CTLs both in vitro and in vivo, they were incapable of eliciting cross-protective tumor immunity when tumor immunizations and challenges were made entirely in vivo. The state of cross-protective immunity within hyperimmune mice is directed toward shared tumor-associated transplantation antigens (TA-TAs). Unlike the common TAAs, these particular determinants are related to the induction etiology of the tumor. Previous reports have suggested that the suppressor T lymphocytes (Ts cells) present in UV-treated animals possess functional specificity for the common TATAs expressed by UV tumors. Since UV-induced Ts cells were capable of blocking the reexpression of an in vivo state of cross-protective immunity between two MCA tumors that did not express UV tumor TATAs, we now believe that these cells recognize the common TAAs shared by UV and MCA tumors. Collectively, these data define at least two different classes of common tumor antigens expressed by UV and chemically induced tumors. These antigenic determinants are functionally defined as the TATAs and the common TAAs. The shared TATA function in vivo as rejection antigens and are restricted to tumors induced by the same carcinogenic agent. In contrast, the common TAAs shared by UV and chemically induced tumors are not only recognized by CTLs but more importantly function as immunoregulatory determinants. The importance of these common tumor antigens in host-tumor interactions is discussed.

Skin immunology: The Achilles heel to transdermal drug delivery☆

Abstract There are numerous advantages associated with the development of transdermal delivery systems for pharmacologically active drugs and chemicals. Before the potential of transdermal drug delivery can be fully realized, however, researchers are being forced to cope with the problems associated with the development of allergic contact dermatitis and other types of immune responses that can emerge in individuals receiving this form of therapy. This appears to be a unique problem of the transdermal delivery systems since the same agents, given orally or by injection, are accepted by the body without immunological incident. The development of an immune response to a trans dermally delivered drug could have serious implications. It is conceivable that in addition to the immediate problem of allergic contact dermatitis, an immune response could develop that could neutralize the drugs activity. As a result, the sensitized patient may no longer derive any clinical benefit from its usage or that of chemically related compounds. The reasons why and how such skin-associated immune responses are induced, as well as an overview of the skin as an immunologically important organ system, will represent the major focus of this presentation.

Description of and treatment to inhibit the rejection of human split-thickness skin grafts by congenitally athymic (nude) rats.

Gradual rejection of topically engrafted human split-thickness skin grafts (HSTSG) occurred in greater than 90% of congenitally athymic (nude) rats between 21 and 42 days of grafting. Engraftment and rejection of HSTSG is accompanied by a partial restoration of some cell-mediated immune components, the mixed lymphocyte response and lysis of human target cells. Histologic features of the rejection process were those seen in a host-versus-graft reaction. Immunofluorescent analysis of skin undergoing rejection demonstrated IgG at the basement membrane zone in most grafts. Nude rats rejecting HSTSG had circulating IgG which bound to the basement membrane zone and blood vessels of human skin. Nude rats treated with cyclosporine injections for 21 days had an enhanced survival of HSTSG, 120 or more days.

Arecoline-induced skin inflammation: irritant or allergic dermatitis?

Abstract A severe skin inflammatory reaction halted the development of a transdermal device to systemically deliver arecoline, a cholinergic agonist, for use in the management of a human neurological disorder. This report demonstrates that the skin reaction is most likely an allergic contact dermatitis (ACD) exacerbated by inflammation, as characterized by classical immunological tests employing inbred mice: abdominal skin sensitization followed by ear challenge and ear challenge of recipients of lymphoid tissues from previously sensitized donors. Chemical analysis of the parent compound in three vehicles was performed to determine the chemical stability of the prepared solutions and the antigen specificity of the murine ACD response. Arecoline was hydrolyzed to the pharmacologically inactive metabolite, arecaidine, to the greatest extent in aqueous vehicles. ACD reactions were greatest when mice were both topically sensitized and challenged with arecoline. In contrast, arecaidine, the hydrolyzed product, did not have immunological activity, but was capable of producing local inflammation in a dose-dependent manner upon subcutaneous injection. These data support the mechanistic hypothesis that upon absorption into skin, arecoline induces a local inflammatory response and a systemic ACD response. Influx of lymphocytes to an arecoline-treated skin site likely mediate ACD through the combined inflammation produced by arecoline and arecaidine and recognition of arecoline as an immunogen.