Esteropeptidase and thymotropic activity of a protein isolated from the mouse submaxillary gland

Extra-thymic immature T cells: development in polyoma virus-induced murine salivary gland tumors

Lymphocyte infiltrates which occur in some polyoma virus-induced murine salivary epithelial tumors are characterized. The lymphocytic infiltrates within the salivary tumors resemble cortical thymocytes with the phenotype PNA+, Thy-1.2 bright, Ly-2+L3T4+, Ly-1 dim, H-2Kdim, KJ16-133-. The salivary lymphocytes showed proliferation based on analysis of RNA and DNA content. Because thymocytes lose the immature phenotype before leaving the thymus, we propose that the salivary tumor infiltrates result from the intra-tumoral differentiation of blood-derived prothymocytes into "cortical thymocytes". Histologic examination of the salivary tumors indicates expression of class II major histocompatibility antigen on the tumor epithelium which may be essential in establishing the extra-thymic T lymphocyte-inductive microenvironment within the tumor.

The effects of submandibularectomy on the thymus and T-cell system of mice

Functional changes of the T-cell immune system in submandibularectomized (SMx) male mice of CBA/H strain were analyzed three or four weeks after treatment. Thymuses and spleens were weighed and morphologically examined by light microscopy. We tested proliferation rates of thymocytes and splenocytes (stimulated by Con A and PHA) and cytotoxic activity of T lymphocytes in SMx, CBA/H (H-2k) mice by means of the rejection test of allogeneic skin graft (Balb/c, H-2d) and a microcytoxicity to allo-antigens of EL-4 tumor cells (H-2b). Results showed a reduction of the weights of the thymus and spleen. However, there was increased functional capacity of the thymocytes--expressed as increased proliferation rates of the stimulated thymocytes, increased microcytotoxicity to allo-antigens of EL-4 tumor cells in vitro, and a reduction of the survival period of skin allografts in vivo. No morphological changes other than a reduction in both the cortex and medullar of the thymus were observed. The subpopulational changes within the T-cell system because of SMx indicate that the morphological atrophy could be just a consequence of SMx.

Molecular species of epidermal growth factor carrying immunosuppressive activity

The suppression of antibody formation to sheep red cells in mice by partially purified fractions of mouse submaxillary gland was shown to be caused by epidermal growth factor (EGF). Purification of EGF by the method of Savage and Cohen resolved three components referred to as EGF a, EGF b, and EGF c. All three induced premature eye opening in neonatal mice, but only EGF a (identified as EGF 1-53) had full immunosuppressive activity. EGF c was shown by micropeptide mapping of chymotryptic and thermolytic digests and amino-terminal analysis to differ from EGF a only by the presence of beta-aspartyl instead of an asparaginyl residue. EGF b differed from EGF a in that it lacked the N-terminal asparagine. EGF shortened enzymatically at its carboxy terminal by two or five amino acids did not have any immunosuppressive activity. These findings suggest that, in contrast to some other biological effects of EGF, intact amino and carboxy terminals are required for the expression of immunosuppressive activity.

Immunosuppressive activity of submaxillary gland extracts of the mouse. I. Effect on antibody formation in response to sheep red blood cells

Aqueous extracts of mouse submaxillary glands yield six peaks on Sephadex G-75 columns, each containing several molecular species. Two of these fractions (III and IV) have a profound effect on the immune response. When given a day before immunization with sheep erythrocytes, the number of antibody-producing cells is reduced ten-fold or more, and the switch from IgM to IgG is virtually absent. Administration two days before or on the day of immunization results in about 50% depression; outside this range there is no effect. The dose-response curve is of sigmoid shape, with the median at about 0.5 mg of fraction III/40 g mouse, reaching an asymptote after doses of greater than or equal to 5 mg at about 5% of the response of untreated mice. Depression of the primary response does not prevent the development of immunological memory: the secondary response is typical in the early and predominant appearance of IgG-producing cells, although their numbers are somewhat lower than in the controls which received no treatment before primary immunization. Treatment on the day before boosting abrogates the secondary response. The immunotranquilizer from mouse submaxillary glands acts equally well on syngeneic and allogeneic recipients, affecting the earliest stage of the immune response. The results are compatible with the induction of a temporary block in the development of helper T cells.

Biochemical and morphological studies of rat submandibular gland: I. Centrifugal fractionation of granule-rich fraction

Submandibular glands from male rats were homogenized in 0.34 M sucrose and 0.5 mM ethylenediaminetetraacetic acid in 10 mM HEPES buffer at a pH of 7.4. The extract was centrifuged and filtered through nuclepore filters to prepare a granule-rich fraction. Electron dense zymogen granules constituted approximately 85% of the particles in this fraction which also contained about a third of the total alkaline esterase activity in the gland.