David Steinmuller

Expression of I-region gene products on mouse tail epidermis cells

Abstract Mouse epidermal cells express Ia antigens. Epidermal cells from C3H and B10. A mice express I-A and I-E region gene products. Products associated with I-B and I-J were not detectable. A weak reaction was seen with anti-I-C sera. Products of the I-A region appear to be preferentially expressed when compared to I-E-region gene products. Ten percent of epidermal cells possess IgG-specific Fc receptors and 15% of epidermal cells can phagocytize latex particles. Our studies suggest that Ia-positive epidermal cells in mice are not necessarily limited to Langerhans cells.

Further studies on the use of mouse epidermal cells for the in vitro induction and detection of cell-mediated cytotoxicity.

Abstract Mouse epidermal cells (EC) and lymphoid cells (LC) were compared as targets of cellmediated cytotoxicity (CMC) in short-term chromium release assays where attacker cells were generated in primary mixed cultures using irradiated allogeneic EC or LC as stimulators. Three patterns of relative susceptibility to lysis of the two types of target cells were observed: (i) significantly greater lysis of LC than of EC targets; (ii) significantly greater lysis of EC than LC targets; and (iii) approximately equal susceptibility to lysis of the two targets. The first pattern was primarily associated with LC stimulators, whereas the second and third patterns were almost invariably associated with EC stimulators. Factors possibly contributing to the differences in in vitro immunogenicity and susceptibility to CMC of EC and LC were investigated, including the alteration of EC surface antigens during the trypsinization required to prepare EC suspensions, the differential expression of shared alloantigens, or the restricted expression of tissue-specific alloantigens on the two types of cells. Tests with intact and trypsinized LC on the one hand and fresh and short-term cultured EC on the other indicated that trypsinization is not responsible for the basic differences between EC and LC detected in the in vitro assays. Antibody absorption tests demonstrated that although EC and LC express approximately equal quantities of the cell surface antigens determined by the H-2D region of the H-2 complex, LC express significantly greater quantities of the antigens determined by the H-2K and I regions. In addition, the results of cold target inhibition tests suggest that tissue-specific antigens on both EC and LC also influence their relative immunogenicity and susceptibility to lysis.

Cellular autoimmunity in psoriasis and lichen planus

The objective of this investigation was to determine whether specific cellular recognition of the epidermis is associated with the human skin diseases, psoriasis and lichen planus. Epidermal cells (EC) obtained from biopsies of involved and uninvolved skin of patients with these diseases were used as stimulators and targets for autologous peripheral blood mononuclear cells (PBMC) in assays of three conventional manifestations of cellular immunity: lymphocyte transformation, leukocyte migration-inhibition and cell-mediated cytotoxicity. Parallel tests were conducted with autologous PBMC as stimulators to ascertain the tissue specificity of the reactions evoked by autologous EC. Similar assays were conducted with EC and PBMC from a large group of normal subjects, and the results were compared to those of the dermatology patients by rigorous statistical analyses. No evidence of lymphocyte-mediated cytotoxicity towards autologous EC was obtained with any of the subject groups, but autologous EC, and to a lesser extent PBMC, of the psoriasis patients, but not of the other two groups, evoked significant lymphocyte transformation. These results were obtained only with patients on Goeckerman therapy, raising the possibility that they were a manifestation of the treatment (topical coal-tar and ultraviolet light irradiation) rather than of the disease, although reasons are presented why this is unlikely. Clearer evidence of disease-associated autoimmunity was obtained in the leukocyte migration-inhibition assays, where autologous EC, and to a lesser extent, PBMC, of the psoriasis patients in general, not just those on Goeckerman therapy, and not those of the lichen planus patients or of the normal subjects, stimulated the release of a leukocyte migration-inhibition factor. These results support the concept of a central role for T-cell mediated autoimmunity in the pathogenesis of psoriasis.

Cell-mediated cytotoxicity to non-MHC alloantigens on mouse epidermal cells

Mice of the C3H/He and A non-H-2 backgrounds are disparate from mice of the B10 background for the tissue-restricted, non-H-2 alloantigen of epidermal cells (EC), Epa-1, that is expressed by EC but not by lymphocytes (LC), as well as for a number of other alloantigens of the B10 background that are expressed by both EC and LC, generically referred to as “lymphocyte/epidermal alloantigens” (LEA). In this study, we compared the ability of various H-2 congenic strains on the C3H or A backgrounds to mount cytotoxic T-lymphocyte (CTL) responses to EC from H-2 compatible mice of the B10 background. High responses to Epa-1 were detected only in the H-2aand H-2khaplotypes; H-2b, H-2o1, H-2s, H-2t1, and H-2t2 haplotypes were nonresponders to Epa-1. High responses to LEA were detected in H-2a, H-2b, H-2s, H-2t1, and H-2t2 haplotypes; H-2kand H-2o1 were nonresponsive to LEA. Analysis of the H-2K, I and D region alleles of responders indicates that H-2Kkis essential for anti-Epa CTL responses, whereas Dd, Db, or Kswere all permissive for strong anti-LEA responses. The ability to mount a given CTL response was not associated with differences in I-region alleles. These results are discussed in terms of K/D region products serving as Ir-gene products for CTL and in determining the apparent tissue-specificity of CTL.

The screening of non-H-2 congenic lines forSk loci

Thirty-seven histocompatibility congenic lines of mice, including at least 27non- H-2 lines, developed by Bailey on the C57BL/6 background, were screened for loci determining Sk (skin-specific) histocompatibility antigens. Background strain hosts were inoculated with lymphoid cells from the congenic lines and subsequently challenged with skin test grafts from the same donors. Comparison of the survival times of these test grafts with those of first- and second-set skin grafts in the same donor-host combinations suggests that the lymphoid cells from 35 of the congenic lines apparently immunized or tolerized at least some of the hosts. Thus, the histocompatibility antigens involved were shared by lymphoid cells and skin, and by definition could not be Sk antigens. The tests were indecisive with two of the non-H-2 lines, but if Sk antigens were involved, their contribution to the immunogenicity of conventional skin allografts probably was negligible. Hence ifSk congenic lines are desired, they probably will have to be developed on their own by procedures specifically designed to select for Sk antigens of significant immunogenicity.

Lysis of mouse macrophages, fibroblasts, and epidermal cells by epidermal alloantigen-specific cytotoxic T lymphocytes: Effect of culture and inflammatory agents on Epa-1 expression

The expression of Epa-1, a tissue-restricted non-major histocompatibility complex (MHC) alloantigen, on CBA epidermal cells (EC), fibroblasts (FB), and macrophages (M phi) was investigated using bulk-cultured and clonally-derived anti-Epa-1 cytotoxic T lymphocytes (CTL). Epa-1 was readily detected on freshly trypsinized and 24-hr-cultured EC, and on skin FB cultured for 1-3 weeks. In contrast, fresh peritoneal (PE) M phi were specifically resistant to Epa-1 CTL but became susceptible after 12-24 hr in culture. Epa-1 expression by PE M phi also could be induced in vivo by M phi-activating agents such as concanavalin A or Bacillus Calmette-Guérin (BCG), but not by the sterile inflammatory agents peptone broth or thioglycolate, suggesting a correlation between Epa-1 phenotype and M phi activation. From this and from parallel studies of spleen cell M phi it is concluded that Epa-1 may be a strain-specific marker for activated M phi in the mouse, as well as an inducible histocompatibility antigen in vivo.

Cell-mediated cytotoxicity to non-MHC alloantigens on mouse epidermal cells: IV. An alloantigen shared with B cells but not T cells

Abstract Cytotoxic T lymphocytes raised by immunization of C3H mice with AKR epidermal cells (EC) strongly cross-react with AKR lymphocyte (LC) targets, provided the LC are cultured prior to use as target cells. By nylon-wool separation, negative-selection, positive-selection, and cold-target inhibition methods, we have identified B cells as the susceptible LC targets and determined that their antigenicity requires a culture-induced, proliferation-independent change in antigen expression. Questions concerning the nature of the culture-induced event, the identity of the B-cell alloantigen, and its concomitant expression by EC are discussed.