No abstract

A large number of CD4+ T cell clones, obtained from peripheral blood T lymphocytes by direct limiting dilution, allowed us to address the question whether functional heterogeneity exists within the human CD4+ T cell subset. Cytotoxic capacity of cloned T cells was analyzed with the use of anti-CD3 antibodies and target cells bearing FcR for murine IgG. 6 of 12 CD4+ clones obtained were able to lyse Daudi or P815 cells in the presence of anti-CD3 antibodies. The remaining six CD4+ T cell clones tested did not display anti-CD3-mediated cytotoxic activity and did not acquire this cytotoxic capacity during a culture period of 20 wk. In the absence of anti-CD3 mAb, no lytic activity against Daudi, P815, and K562 target cells was observed under normal culture conditions. Phenotypic analysis of these two distinct types of CD4+ T cells did not reveal differences with regard to reactivity with CDw29 (4B4) and CD45R (2H4) mAbs that have been described to recognize antigens associated with helper suppressor/inducer (respectively) CD4+ cells. The CD4+ clones without anti-CD3-mediated cytotoxic activities (Th2) consistently showed a high expression level of CD28 antigens, whereas the cytotoxic clones (Th1) expressed low amounts of CD28. Th1 CD4+ clones did produce IL-2, IFN-gamma, and TNF-alpha/beta, whereas the Th2 T cell clones produced minimal amounts of IL-2 and only low levels of INF-gamma and TNF-alpha/beta in response to anti-CD3 mAbs and PMA. Although not all CD4+ clones did release IL-4, there was no correlation with cytotoxic activity. Moreover, as compared with the Th1 CD4+ clones, Th2 CD4+ T cell clones proliferated moderately in response to immobilized anti-CD3 mAbs. However, proliferation reached the level of the cytotoxic clones when anti-CD28 mABs were present during culture. Both CD4+ subsets provided help for B cell differentiation upon stimulation with anti-CD3 mAbs. Our data suggest that the human CD4+ subset, in analogy to the murine system, comprises two functionally distinct T cell subpopulations, both of which are able to exert helper activity for polyclonal B cell differentiation, but which differ in cytotoxic capacity, lymphokine production, and requirements for proliferation. A function for these two types of T cells in the immune response is discussed.

The tetrasaccharide repeating unit of the capsular polysaccharide of Kkebsiella serotype 11, K11PS, comprises the following sequence: [-*3)-I8-D-GlcpA-(1--.3)-a-D-Galp-(1--3)-4-D-Glcp-(l--I with a 4,6-0-(1carboxyethylidene)-a-D-galactopyranosyl residue linked to 0-4 of the glucuronic acid residue. Octasaccharide (OS) derived from K11PS by bacteriophage +11-associated glycanase, was coupled to bovine serum albumin and to keyhole limpet hemocyanin. The immunogenicity of various antigens after intraperitoneal immunization was studied by measuring the levels of circulating antibodies. Injection of BALB/c mice with K11PS resulted in induction of 2-mercaptoethanol-sensitive immunoglobulin M antibodies. The responses observed in BALB/c nulnu mice and in male (CBA/N x C3H/HeN)Fl mice indicate that K11PS is a thymus-independent type 2 antigen. Immunization of BALB/c mice with either OS-bovine serum albumin or OS-keyhole limpet hemocyanin resulted in the induction of circulating 2-mercaptoethanol-resistant immunoglobulin G antibodies.Results in BALB/c nulnu mice indicate that the OS-protein conjugates are thymus-dependent antigens. Since the OS-keyhole limpet hemocyanin conjugate induced antibodies in both (CBA/N x C3H/HeN)Fl females and males, we propose to refer to this kind of antigen as a thymus-dependent type 1 antigen, whereas OS-bovine serum albumin, which evoked immunoglobulins in (CBA/N x C3H/HeN)Fl females only, can be referred to as a thymus-dependent type 2 antigen.Bacterial polysaccharides are generally considered to be thymus-independent (TI) antigens (4, 6) and are characterized by the induction of mainly immunoglobulin M (IgM) and IgG3 antibodies after primary immunization (17, 29), without the induction of immunological memory (35). Moreover, the immune response toward TI antigens is developed only at later stages of the ontogeny, which has important consequences for the vaccination of neonates (27,35).For vaccinations aiming at long-lasting protection against diseases, it would be desirable to immunize with thymus-dependent (TD) antigens (35). TD antigens are supposed to induce immunological memory and thus to provoke a state of prolonged resistance to infections (36). Furthermore, the development of TD forms of a particular TI antigen raises the possibility of immunizing young animals with more success than with the TI antigen itself.In earlier experiments with Streptococcus pneumoniae type 3 capsular polysaccharide (S3PS) and hexasaccharideprotein conjugates, we showed that the S3PS behaved as a TI antigen, whereas the hexasaccharide-protein conjugates behaved as TD antigens (35). To extend the results obtained with S3PS and hexasaccharide-protein conjugates of S. pneumoniae, we used the capsular polysaccharide of Klebsiella serotype 11, K11PS, as a novel model antigen. This polysaccharide was chosen because of the availability of bacteriophage +11-associated glycanase, which could be used to depolymerize K11PS. Enzymatic digestion of K11PS results in the cleavage of the ,(1-3-3) glycosidic linkage betw...

Abstract. The synthesis of a series of six less-lipophilic analogues of the a-glucosidase inhibitor N-decyl-I-deoxynojirimycin (N-decyl-dNM, 5) is described. With the incorporation of a single oxygen atom, particularly at position seven in the N-decyl side-chain to give N-(7-oxadecyl)-dNM (8), the therapeutic ratio (a-glucosidase I inhibitory activity over toxicity in HepG2 cells) increases considerably. Compound 8 inhibits purified porcine liver a-glucosidase I with an IC,, value of 0.28 p M . The position of the oxygen atom in the N-decyl side-chain is of importance since N-(3-oxadecyl)-dNM (7) is less active than 8 and, moreover, is toxic to HepG2 cells at 3 mM. Subsequently, the synthesis of eight ester derivatives of N-(7-oxadecyl)-dNM is described. All of these ester analogues are less active a-glucosidase inhibitors than the parent compound 8 in HepG2 cells. The compounds were further analyzed for antiviral and immunomodulatory activity in uitro. I t is found that the most potent a-glucosidase I inhibitor from this study N-(7-oxadecyl)-dNM (8) inhibits HIV-1 -induced syncytia formation and lymphocyte proliferation in uitro. Finally, compound 8 was investigated in uiuo. N-(7-Oxadecyl)-dNM (8) reduced adjuvant-induced arthritis in rats making this compound a potential candidate for treating autoimmune diseases like rheumatoid arthritis.

No abstract