bluuebunny/crossref_metadata_2025 huggingface dataset:
Protection against Schistosoma mansoni achieved by immunization with sonicated parasite
Authors: Horowitz Shulamit , Smolarsky Moshe , Arnon Ruth
Published: February 2007

Partial protection of (C57BL/6 x DBA/2)F1 mice against infection with Schistosoma mansoni has been achieved by immunization with small amounts (0.2 to 2.0 μg) of crude cercarial sonicate adsorbed on aluminium hydroxide gel adjuvant (alum). A decrease of 34–90% in the adult worm burden of the immunized mice, as compared to that of untreated mice or those injected with adjuvant alone, has been found in five experiments by liver perfusion six weeks after percutaneous challenge infection. High titers of anti‐cercarial IgE antibodies have been found in the sera of the immunized mice by two independent techniques, radioimmunoassay and degranulation of rat basophilic leukemia cells (RBL‐2H3), determined by 3H‐serotonin release. By counting the live worms in the lungs of immunized and uniummized mice on days 4‐7 after infection it was observed that the schistosomula were killed before they reached the lungs, probably at the skin. Mice immunized with the same amounts of cercarial antigen in Freund's complete adjuvant were not protected against infection with S. mansoni. These animals developed high titer of total anti‐cercaria antibodies (determined by radioimmunoassay) but had low levels of antiparasite IgE. The possible role of IgE in protective immunity is discussed.
Regulation of in vitro cytotoxic T lymphocyte generation. II. Demonstration of noncytotoxic alloantigen‐specific suppressor T lymphocytes
Authors: Schwartz Anthony , Sutton Sandra L. , Gershon Richard K.
Published: February 2007

Both allospecific suppressor T lymphocytes (TsS) and nonspecific suppressor T lymphocytes (TsN) are activated in alloantigen‐stimulated mixed leukocyte cultures (MLC). TsS and TsN can suppress cytotoxic T lymphocyte (CTL) induction upon transfer to fresh (second) MLC stimulated by the same alloantigens as in the first MLC (TsS or TsN) or by third‐party alloantigens (TsN only). Evidence that TsS and TsN functions are performed by different T cell sets has been restricted to radioresistance of the former but not the latter. Separation of TsS from CTL has proven even more difficult. Methods are reported here which have allowed in vitro induction and functional separation of TsS from CTL and TsN in a totally allogeneic system. TsS are resistant to combined exposure to pyrilamine, a histamine1 antagonist and local anesthetic, during suppressor cell induction, and to X or γ irradiation thereafter, while CTL precursors (CTL‐P) and TsN are more sensitive to such treatments. This allowed us to use these treatments to generate TsS that are not contaminated with functional CTL, CTL‐P or TsN. These data show that TsS regulate CTL induction by interacting with responding cell populations, rather than by cytotoxic depletion of stimulator cells.
Syngeneic sensitization of mouse lymphocytes on monolayers of thyroid epithelial cells. III. Induction of thyroiditis by thyroid‐sensitized T lymphoblasts
Authors: Charreire Jeannine , Michel‐Bechet Marc
Published: February 2007

During in vitro sensitization of CBA spleen lymphocytes on syngeneic monolayers of either thyroid epithelial cells (TEC) or fibroblasts, stimulation occurs, as assessed by thymidine incorporation and lymphoblast generation. When lymphoblasts generated on syngeneic TEC are injected either into thyroid lobes of intact CBA recipients or i.v., thyroiditis appears at least 21 days after injection. Thyroiditis is assessed by both optical and electron microscopic blind studies and by the presence of antibodies in the sera directed against mouse thyroglobulin. In contrast, control animals which received identical numbers of lymphoblasts generated on syngeneic fibroblasts behaved as normal. Thyroiditis was also induced using pure thyroid‐sensitized T lymphoblasts. This is the first report showing the role of T lymphocytes in the induction of experimental autoimmune thyroiditis.
Soluble factors in tolerance and contact sensitivity to 2,4‐dinitrofluorobenzene in miceIV. Characterization of migration inhibition factor‐producing lymphocytes and genetic requirements for activation
Authors: Moorhead John W. , Murphy Juneann W. , Harvey Robert P. , Hayes Roberta L. , Fetterhoff Terry J.
Published: February 2007

The production of migration inhibition factor (MIF) in vitro by lymph node cells from mice with contact sensitivity to 2,4‐dinitrofluorobenzene (DNFB) was investigated. MIF activity of cell‐free culture supernatants was measured using a micro, indirect “hanging‐drop” assay system. We found that DNFB‐sensitized lymph node cells are stimulated to produce MIF by co‐culture with DNP‐labeled spleen cells or splenic adherent cells. The stimulation was quantitatively antigen‐specific, as co‐culture with TNP‐spleen cells or TNP‐splenic adherent cells induced only low levels of MIF activity. Pretreating the immune lymph node cells with different antisera plus complement, before addition of DNP‐spleen cells, showed that MIF production is dependent on Ia− T cells. Additional experiments showed that in order for the T cells to be stimulated, homology at the I‐A subregion of the major histocompatibility complex between the T cells and DNP‐spleen cells is required. Collectively, these results correlate with our previous finding that transfer of contact sensitivity is mediated by Ia− T cells and indicate that both tests, i.e., transfer in vivo and MIF production in vitro, are measuring effector functions of the same T cell subset.
Analysis of low natural killer cell activity in 89Sr‐treated mice
Authors: Mellen Paul F. , Lust John A. , Bennett Michael , Kumar Vinay
Published: February 2007

Treatment of mice with the long‐lived bone‐seeking radioisotope 89Sr results in the selective irradiation and destruction of the bone marrow. This is accompanied by a marked reduction in natural killer cell activity against YAC‐1 lymphoma [NK(YAC‐1)]. To test for the presence of cellular suppressors of NK(YAC‐1) in 89Sr‐treated mice, in vitro and in vivo cell mixture protocols were used. In vitro, we did not observe any specific inhibitory effect of spleen cells from 89Sr‐treated mice on NK(YAC‐1) activity of normal spleen cells. The NK(YAC‐1) activity of 89Sr‐treated mice, measured in vivo by their ability to clear radiolabeled YAC‐1 cells from the lungs, was impaired. However, spleen cells from 89Sr‐treated mice, when adoptively transferred with normal spleen cells, failed to inhibit the NK(YAC‐1) activity of the latter in the lung clearance assay. Further, when normal spleen cells were injected into 89Sr‐treated mice, the ability of the transferred cells to mediate in vivo activity was not suppressed in the 89Sr‐treated host. These experiments support the suggestion that the low NK(YAC‐1) activity in 89Sr‐treated mice is not mediated by suppressor cells, but may be due to the destruction of the marrow microenvironment which is essential for the generation of functional NK(YAC‐1) cells.
The induction of B cells refractory to antibody‐specific immunoregulation
Authors: Speck Nancy A. , Pierce Susan K.
Published: February 2007

Subsequent to primary immunization with a hapten‐carrier conjugate, and concomitant with an initial antibody response to that antigen, a regulatory mechanism is induced that specifically limits the stimulation of hapten‐specific primary B cell responses through the recognition of B cell antibody. Nonimmune B cells are sensitive to this regulation, while secondary B cells are refractory to its suppressive effects. Experiments were conducted to determine the conditions under which refractory B cell populations are generated. B cells from BALBlc and athymic BALB/c nu/nu mice were examined following immunization with the T‐dependent antigen dinitropheny‐lated (DNP) hemocyanin and the T‐independent antigen DNP‐Ficoll to assess the T cell dependence of the generation of refractory B cells. Evidence is presented that this process is not dependent on the presence or participation of T cells during in vivo immunization, since both T‐dependent and T‐independent antigens have the potential to induce a refractory B cell population. However, under certain circumstances, T cells can regulate the induction of refractory B cells during in vivo immunization. In addition, it was determined that the immunoregulatory phenomenon can be induced following immunization with both T‐dependent and T‐independent antigens.
Target‐effector interactions in the rat natural killer cell system. I. The measurement of cytotoxicity at the single Cell level
Authors: Flexman James P. , Shellam Geoffrey R.
Published: February 2007

Optimal conditions have been developed for measuring interactions at the single cell level between effector cells and target cells in the rat NK cell system. Conjugates were formed between splenic leukocytes and target cells to determine the percentage of target binding cells, and after immobilization of the conjugates in agar, single lytic interactions were measured by the uptake of trypan blue by dead target cells. Cytotoxic effector cells were expressed as a percentage of target binding cells. Factors which influenced conjugate formation were the ratio of effector to target cells, temperature, centrifugation and the conditions of culture of the target cells. When comparing a number of rat and mouse strains with various levels of natural killer cell activity, there was found to be a good correlation between the number of target binding cells and cytotoxicity in the standard 51Cr‐release assay in rats, but in mice the removal of nylon‐adherent cells was required to achieve a reasonable correlation. However, 60–70% of the cytotoxicity was lost on nylon fractionation, making this approach of doubtful value. The target‐binding cell and cytotoxic effector cell assays were used in conjunction with the 51Cr‐release assay to study the specificity, rat strain variation and ontogeny of natural killer cells. During ontogeny target binding cells reached adult levels sooner than did cytotoxic effector cells. The greatest development of natural killer cells occurred during the first 3 weeks of life; the number of cytotoxic cells per spleen increased 138‐fold up to 21 days of age, compared with an 11‐fold increase between 21 days and 9 weeks of age.
A comparison of two anti‐neuraminidase monoclonal antibodies by complement activation
Authors: Holmes Kerry T. , Hampson Alan W. , Raison Robert L. , Webster Robert G. , O'Sullivan William J. , Mountford Carolyn E.
Published: February 2007

The specificities of two anti‐neuraminidase monoclonal antibodies have been compared by their ability to fix complement. They were found to differ to some extent in their reactivity with a range of N2 influenza viruses. Thus, as in the case of anti‐hemagglutinin antibodies, anti‐neuraminidase monoclonal antibodies are able to detect subtle structural changes in the viral antigen. Although both monoclonal antibodies fixed complement with intact virus, neither one fixed complement when complexed with isolated neuraminidase “heads”.
Are Tγ cells of myelomonocytic lineage?
Authors: Astaldi Alberto , Van De Griend René J. , Schellekens Peter Th. A. , Vossen Jaak M.
Published: February 2007

To evaluate the cell lineage from which Tγ cells derive by means other than cell membrane markers, the rare situation of human chimerism was studied. In patients with severe combined immunodeficiency who have been successfully treated by bone marrow transplantation, the occurrence of split take has been well documented: whereas myelomonocytic hemopoietic cell lines remain of host origin, the T lymphoid compartment is of donor origin, and the B lymphoid compartment may be either of host or of donor origin. We have studied the Tγ cells of two patients successfully treated by bone marrow transplantation from donors of the opposite sex with respect to the sex chromosome pattern, the binding of OKM1 and OKT3 monoclonal antibody and the killer (K) and natural killer (NK) cell activities. All Tγ cells of both patients were found to be of donor origin. These Tγ cells contained two serologically distinct subpopulations, one OKM1+, OKT3+, the other OKM1+, OKT3−, as was also found in normal persons. However, the ratio between these two subpopulations is < 1, whereas the ratio in these patients was > 1. Furthermore, the patients' Tγ cells displayed strongly reduced K and NK activities (< 5% of normal). It was concluded that at least part of the OKM1+, OKT3− and the OKM1+, OKT3− Tγ cells are derived from other than the myelomonocytic lineage, presumably from the lymphocytic lineage. The origin of the K‐ and NK‐active Tγ cells, however, cannot be conclusively determined from these experiments. The findings also imply that the antigen detected by OKM1 should no longer be regarded as exclusively present on myelomonocytic cells.
Migrant μ+δ+ and static μ+δ− B lymphocyte subsets
Authors: Gray David , MacLennan Ian C. M. , Bazin Hervé , Khan Mahmood
Published: February 2007

Immunoglobulin isotype expression in isolated lymph node (LN), spleen and blood lymphocyte suspensions was assessed in rats. The proportion of μ+δ− B cells in spleen (34%) was approximately twice that in blood and LN. Immunohistological examination of spleens showed the cells of the marginal zones to be predominantly μ+δ−. On the other hand, μ+δ+ B cells were mainly confined to the follicles in both spleen and LN. These follicles had a minor μ+δ− component.

The migratory properties of B cells with these two phenotypes were assessed by depleting lymphocytes migrating through the white pulp of rat spleen. This was achieved by placing a 32P‐impregnated β‐emitting polythene strip over one half of the spleen. Examination of the nonirradiated half of the spleen, LN and peripheral blood after 12 days irradiation showed selective loss of δ+ B cells. The μ+δ− cells of the splenic marginal zone were numerically unaltered. There was also a substantial residual μ+δ− B cell presence in the small lymphocyte compartment of follicles of LN and spleen in depleted animals. In addition, the blood selectively retained a μ+δ− B cell component. This was not derived from the spleen, as μ+δ− blood B cell numbers were sustained even where both halves of the spleen were irradiated. It is concluded that: (a) the major static B cell component of spleen and LN is μ+δ−, (b) that most if not all δ+ B cells repeatedly migrate through the spleen and (c) there is a blood‐born μ+δ− component which is resistant to depletion by splenic irradiation.
Natural killer cell activity in the rat. Analysis of effector cell morphology and effects of interferon on natural killer cell function in the athymic (nude) rat
Authors: Reynolds Craig W. , Timonen Tuomo T. , Holden Howard T. , Hansen Carl T. , Herberman Ronald B.
Published: February 2007

Athymic (nude) rats were found to have increased levels of natural killer (NK) activity, 3− to 5−fold higher than in euthymic rats. Studies were performed to determine the nature of the NK cells in these animals and the basis for their increased cytotoxic reactivity. Large granular lymphocytes (LGL), which were previously shown to be the NK cells in euthymic rats, were increased 2‐ to 7‐fold in the peripheral blood and spleen of nude rats. The LGL, enriched by centrifugation on discontinous Percoll density gradients, were shown to have augmented NK activity similar to that seen with LGL‐enriched fractions from euthymic rats. These results indicate that the NK cells in euthymic and athymic rats are morphologically and functionally similar, and that the higher NK activity in nude rats appears to be mainly attributable to an increased proportion of effector cells. In a single‐cell cytotoxicity assay, interferon pretreatment of LGL was shown to increase: (a) the percentage of LGL which form conjugates with target cells; (b) the percentage of conjugate‐forming cells which kill; and (c) the kinetics of lysis. Different effects were seen depending on the target cell tested.
surface markers of mono‐and multi‐functional mixed leukocyte culture‐derived T cell clones in man
Authors: Pawelec Graham , Kahle Paul , Wernet Peter
Published: February 2007

Alloactivated human lymphocytes have been cloned by limiting dilution followed by expansion of clonal progeny using interleukin 2. Their differing functional specificities were analyzed in terms of reactivity in primed lymphocyte typing (PLT), cell‐mediated cytotoxicity to normal peripheral blood mononuclear cells or to cell line targets susceptible to lysis by natural killer cells, and finally, suppressive capacity in mixed leukocyte cultures. T lymphocyte clones mediating exclusively PLT, CML or suppression were isolated. In contrast, all clones with natural killer‐like activity were found to be multifunctional, in that they strongly suppressed mixed leukocyte cultures, as well as having variable, although generally weak, activity in PLT and CML. From a total of 148 clones initially screened, about half manifested PLT reactivity. Of these, 60% were restimulated exclusively by determinants associated with the HLA‐D type of the original priming cells, whereas the remainder were restimulated by a variety of different HLA‐D as well as HLA non‐D products. Similar heterogeneity of responses at the clonal level was observed among the populations active in CML. Using monoclonal antibodies, surface marker phenotyping of functionally distinct clones was undertaken in an attempt to correlate surface marker profiles with particular functions. It was found that all clones tested were mature, activated T cells (Lyt‐3+, T28+, OKT3+, HLA‐DR+, HTA1‐1, OKT6−). Many of the clones described here, whether functional in PLT CML, having natural killer‐like or suppressor cell activity, expressed putative “helper/inducer” T cell markers defined by OKT4. The putative “suppressor/cytotoxic” marker OKT8 appeared on some natural killer‐functional clones, but not on CML or suppressor cell clones. Clones with natural killer‐like function were identifiable by their additional unique expression of the antigen detected by the rat monoclonal antibody YD1/48.HLK, whereas the monoclonal antibody M522 reacted selectively with clones having natural killer or CML function, but not with those with PLT or suppressor cell function. These results show that cloned T cells with PLT, CML, natural killer or suppressor activities, derived from MLC, can act as valuable tools in the elucidation of T cell function in vitro. To this end, the correlation of defined function with analysis of cell surface markers using monoclonal antibodies will be of value in dissecting components of human immune responses and determining the functional relevance, if any, of structures detected by such antibodies.
Age‐related alterations of the lymphocyte population in the thymus of (NZB × SJL)F1 mice: Analysis by flow cytofluorometry
Authors: Dumont Francis , Habbersett Robert C.
Published: February 2007

(NZB × SJL)F1 (NS) female mice develop a marked hypertrophy of the thymus in the course of aging. The age‐dependent evolution of the intrathymic lymphocyte population of these mice was monitored in comparison with that of the immunologically normal BALB/c and C57BL/6 strains. The expression of several lymphocyte markers on the surface of the thymic cells was quantitated using single‐ and two‐color flow cytofluorometry analysis. Two main cell types could thus be identified in the thymus of 3‐month‐old mice: a major subset of bright Thy‐1+, Lyt‐1+2−, bright peanut agglutinin (PNA)+ lymphocytes and a minor subset of dull Thy‐1+, Lyt‐1+2−, dull PNA+ lymphocytes. In BALB/c and C57BL/6 mice, the frequencies of these cell types did not significantly vary between 3 and 18 months of age, despite a drop of thymic cellularity. In contrast, in NS female mice the proportion as well as the absolute number of dull Thy‐1+, Lyt‐1+2−, dull PNA+ cells increased while those of bright Thy‐1+, Lyt−1+2−, bright PNA+ cells diminished during the same period. The emergence of new cell types could also be noted in the thymus of aging NS female mice. Thus, in addition to the appearance of dull PNA+, Lyt‐2+ cells and of bright PNA+ cells devoid of T cell markers, there was a high frequency of non‐T cells bearing surface immunogloublin, Ia antigen and receptors for Fc. These data indicate that the thymic hypertrophy of NS female mice reflects the intrathymic accumulation of large numbers of phenotypically mature T and B cells. Such alterations were not detectable in NS male mice.
Ontogenic development of B cell reactivities to cooperative cell signals: Dissociation between proliferation and antibody secretion
Authors: Pettersson Svea , Pobor Grgur , Coutinho Antonio
Published: February 2007

Cloned helper T cell lines, with specificity for “minor” antigens expressed on all B lymphocyte (and macrophage) surfaces were used to study the postnatal development of B cell reactivity to helper T cell cooperative signals. Such helper T cell populations, upon physiologic interactions with “target” B lymphocytes, activate them polyclon‐ally, allowing for the analysis of functional ontogeny independent of V gene repertoires. Due to the high frequency of responding cells, these methods also offer a high level of sensitivity and permit measurement of B cell proliferation in the absence of antibody production.

The results demonstrate that neonatal spleen cells are fully competent to stimulate adult helper T cell responses and that neonatal and adult B cells are comparable in their proliferative responses to cooperative cell interactions. In contrast, a marked deficiency in the ability of neonatal cells to mature to immunoglobulin secretion was observed in the same responses. Since the presence of suppressive activities in neonatal spleen cells could not be demonstrated, it was concluded that “early” B lymphocytes are intrinsically defective in their ability to secrete immunoglobulin upon cooperative induction, whereas they show full competence to expand clonally.
Tumor‐specific T helper activity can be abrogated by two distinct suppressor cell mechanisms
Authors: Howie Sarah , McBride William H.
Published: February 2007

Tumor‐specific helper T cell activity was detected in the spleens of tumor‐bearing mice using a sensitive, simple and reproducible in vitro assay based on those previously described for soluble hapten‐carrier antigens. Helper activity disappears when the tumor is large. This is coincident with the appearance of two distinct types of suppressor cells: (a) T cells which suppress tumor‐specific T helper responses and (b) non‐T cells which are nonspecific in their action.
Secretion of human immunoglobulins by mouse myeloma × Daudi somatic cell hybrids
Authors: Erikson Jan , Croce Carlo M.
Published: February 2007

Somatic cell hybrids between nonproducer mouse myeloma cells and Burkitt lymphoma‐derived Daudi cells that do not secrete human immunoglobulin chains secrete human IgM. The 33 000 dalton protein (P33) is also secreted by the hybrids as part of the IgM molecule. Since P33 and x chains cosegregate in all primary hybrid clones and subclones, it is concluded that they are coded for by the same human chromosome 2. The fact that both P33 and x' chains are immunoprecipitated by specific anti‐human x chain antisera, and that both P33 and x' bands disappear and a single band immuno‐precipitable by an anti‐human x chain antiserum appears in tunicamycin‐treated hybrid cells, suggest that they are differently glycosylated forms of the same polypeptide.
Immunosuppression caused by antigen feeding. I. Evidence for the activation of a feedback suppressor pathway in the spleens of antigen‐fed mice
Authors: Macdonald Thomas Thornton
Published: February 2007

Sheep red blood cells (SRBC) administered by the oral route to normal mice elicited no detectable splenic anti‐SRBC plaque‐forming cell (PFC) response until 8 weeks of antigen feeding. At this time a splenic IgA anti‐SRBC PFC response was detected. On the other hand, spleen cells taken from mice given oral SRBC for 1‐5 weeks showed striking changes in their in vitro anti‐SRBC responsiveness as compared to spleen cells from normal mice. This was evidenced by enhanced early (days 3‐4) in vitro responses, followed by suppressed late (day 5‐6) in vitro responses. Both early enhancement and late suppression were T cell‐mediated. Early enhancement appeared to be mediated by helper T cells of the Lyt‐1+2.3− phenotype. Late suppression was also mediated by Lyt‐1+2.3− cells, but Lyt‐2‐bearing cells had to be present in culture for suppression to occur. Lyt‐2‐bearing cells could be replaced with normal T cells. Furthermore, elimination of cells bearing I‐J‐encoded determinants from the T cell population isolated from the spleens of antigen‐fed mice also partially relieved suppression. Thus, antigen feeding appears to activate a feedback suppressor pathway in which Lyt‐1+2.3−, I‐J subregion determinant‐bearing T cells can suppress immune responses by causing normal T cells to become suppressor effectors. No evidence was found to show that antigen feeding induced Lyt‐1−2.3+ suppressor cells in the spleen, nor were any serum suppressor factors detected.
Effects of 15‐hydroperoxyeicosatetraenoic acid on human lymphocyte sheep erythrocyte rosette formation and response to concanavalin A associated with HLA system
Authors: Gualde Norbert , Rabinovitch Hélène , Fredon Monique , Rigaud Michel
Published: February 2007

The lipoxygenase product hydroperoxyeicosatetraenoic acid (HPETE) has immunosuppressive properties in vitro and in vivo. It was observed that 15‐HPETE inhibit the sheep red blood cell rosette formation and the concanavalin A‐induced blast transformation of human lymphocytes. This inhibition was HLA‐linked. HLA‐B12 subjects were less sensitive than non‐B12 subjects. It is likely that HPETE acids are macrophage mediators which inhibit some lymphocyte functions.
Biosynthesis of murine immunoglobulin D: Heterogeneity of glycosylation
Authors: Vasilov Raif G. , Ploegh Hidde L.
Published: February 2007

The biosynthesis of IgD was studied with special reference to aspects of glycosylation in the B1‐8 δ cell line. This cell line was isolated as a spontaneous class switch variant from an IgM‐producing cell line, B1‐8.μ. B1‐8.δ produces both membrane and secretory IgD. The biosynthesis of IgD is unusual in that there is a large degree of heterogeneity in N‐linked glycosylation, most likely involving the number of glycan sidechains that are attached. Similar findings have recently been documented for human IgD. Further modifications of the oligosaccharide side chains follow the pathways established for numerous other glycoproteins. Under conditions where N‐linked glycosylation was inhibited by tunicamycin (TM), the presence of neuraminidase‐sensitive forms of secretory IgD could be shown. Moreover, secretory IgD from TM‐treated cells was susceptible to mild alkaline hydrolysis. Taken together, these findings argue strongly for the presence of O‐linked, sialic acid‐carrying sugars on murine IgD. Both for O‐ and N‐linked carbohydrate side chains, terminal modifications may occur at a different rate and extent for membrane and secretory IgD. For reasons of comparison we also examined some aspects of IgM biosynthesis in the parental cell line and found our results to be in good aggreement with those reported in the literature. Biosynthesis of H‐2K, D antigens was indistinguishable in B1‐8.H μ and B1‐8. δ, suggesting that the unusual features of IgD glycosylation are inherent to this Ig isotype, rather than the consequence of a different complement of glycosyltransfer‐ases or carbohydrate‐modifying enzymes in the Bl‐8.δ cell line. The use of affinity matrices for purification of immunoglobulins allowed us to estimate relative rates for the formation of IgM and IgD molecules capable of binding antigen. The results obtained suggest that Bl‐8 IgM and IgD follow different assembly pathways, IgM most likely through heavy chain dimer formation followed by light chain addition, and IgD through heavy chain‐light chain dimer formation, followed by assembly into full‐sized molecules. Since B1‐8.μ and B1‐8.δ express identical variable regions and light chains, such differences must be attributed to isotypic differences. Inhibition of glycosylation affected neither secretion nor assembly of either IgM or IgD.
Epitope‐specific regulation. III. Induction of allotype‐restricted suppression for IgG antibody responses to individual epitopes on complex antigens
Authors: Herzenberg Leonore A. , Tokuhisa Takeshi , Herzenberg Leonard A.
Published: February 2007

Maternal antibody to the paternal Igh‐1b (IgG2a) allotype induces chronic suppression for Igh‐1b (1b) production in (BALB/c × SJL)F1 hybrid mice. These mice characteristically remain incapable of producing lb antibody responses until about 3 months of age and then enter a remission phase during which they produce normal 1b antibody responses to antigens introduced initially at this time. Thus young allotype‐suppressed mice do not produce lb antibody responses to dinitrophenylated keyhole limpet hemocyanin (DNP‐KLH) and 1b anti‐ KLH.

The suppression of 1b antibody responses in young allotype‐suppressed mice prevents the expression, rather than the development, of 1b memory for priming antigen epitopes. Furthermore, it not only prevents the expression of such memory cells initially but results in the induction of a continued suppression that specifically prevents their expression after the onset of remission. Thus mice primed with DNP‐KLH while allotype suppression is still active develop normal 1b memory for DNP and KLH but nonetheless fail to produce lb anti‐DNP and 1b anti‐KLH responses, even when restimulated with DNP‐KLH during remission. These mice also fail to produce 1b anti‐DNP when stimulated with DNP on an unrelated carrier molecule, i.e., with DNP‐chicken gamma globulin (CGG).

This suppression is both epitope‐specific and allotype‐specific. That is, although 1b responses to DNP on CGG are suppressed, 1b responses to CGG epitopes on DNP‐CGG proceed normally. Furthermore, there is no suppression of other isotype and allotype responses either to DNP or to the CGG epitopes. These data therefore define an Igh‐restricted epitope‐specific mechanism that can be induced to persistently suppress 1b antibody responses to epitopes introduced initially during active (1b) allotype suppression.
Nature of the antigenic complex recognized by T lymphocytes. VIII. Specific inhibition of the stimulatory capacity of antigen‐pulsed hapten‐modified peritoneal exudate cells by anti‐hapten antibody
Authors: Shevach Ethan M. , Chan Christina , Clement Loran T.
Published: February 2007

When macrophages which were pulsed with soluble protein antigens and then modified with 2,4,6‐trinitrobenzenesulfonic acid (TNBS) were cultured with primed T cells in the presence of anti‐2,4,6‐trinitrophenyl (TNP) antiserum, a marked inhibition of the T cell proliferative response specific for the soluble protein antigen under study was observed. Inhibition of the proliferative response required that the protein antigen under study be easily susceptible to conjugation with TNBS. A lag period of 1‐3 h must elapse following pulse exposure to the protein antigen and prior to TNP modification for anti‐TNP antibody to exert an inhibitory effect, which suggests that processing of antigen in an intracellular site might occur with subsequent reexpression of antigen on the macrophage surface. It was hypothesized that anti‐TNP antibody inhibits T cell proliferation by capping and shedding of TNP‐modified determinants of the nominal antigen as well as TNP‐modified cell surface proteins from the macrophage membrane. The failure of others to demonstrate an effect of anti‐antigen antibody on T cell activation can best be explained as secondary to the low density of antigenic determinants on the macrophage membrane with resultant low‐affinity binding of antibody to antigen.
Human T cell clones specific for tetanus toxoid: Characterization of antigen specificity and HLA restriction
Authors: Schmitt Christian , Ballet Jean‐Jacques , Agrapart Monique , Bizzini Bernard
Published: February 2007

T cell blasts isolated from six‐day cultures of peripheral blood mononuclear cells stimulated with tetanus toxoid (TT) were cloned in a two‐layer agar system in the presence of autologous irradiated PBM (iPBM) and TT. Colonies were individually isolated and expanded in interleukin 2‐containing medium. The antigen specificity of three T cell clones was attested by their capacity to proliferate under restimulation by TT and not by an unrelated antigen. The clones were specific for either the α or the β chain of the toxin. T cells from these clones expressed la determinants and antigens of the helper/inducer T cell subset as defined by anti‐T monoclonal antibodies. In the case of the a chain‐specific clone MA 11 from the donor MA, allogeneic iPBM from HLA‐compatible unrelated donors, including seven donors sharing one HLA DR specificity with MA, were found inefficient as antigen‐presenting cells. A familial study, however, demonstrated that antigen presentation could be obtained using nonautologous cells. The presenting capability of cells from relatives of the donor MA segregated in association with the HLA‐DRw6‐bearing maternal haplotype present in MA. Results suggest that MA 11 cells recognized the antigen in the context of a surface determinant closely linked to HLA‐DRw6.
Characterization of human T suppressor‐inducer, ‐precursor and ‐effector lymphocytes in the antigen‐specific plaque‐forming cell response
Authors: Heijnen Cobi J. , Pot Kees H. , Ballieux Rudy E.
Published: February 2007

Suppression of an antigen‐specific plaque‐forming cell response of human blood lymphocytes can be effected by Tμ+ cells that have been primed previously by antigen in vitro for 6 days. While lacking the capacity to suppress the plaque‐forming response directly, these primed Tμ+ suppressor‐inducer cells stimulate a subpopulation of unprimed Toy− cells to differentiate to Tγ+ suppressor‐effector cells.

The Tμ+, Tγ+ and Tμγ− subsets have been shown to be heterogeneous populations of cells. Therefore, the functionally defined T suppressor‐inducer, ‐precursor and ‐effector cells were characterized by OKT monoclonal antibodies and by the capacity to form rosettes with autologous erythrocytes (ar+). Evidence will be presented that in vitro a T4+μ+ar− cell induces a T8+μγ− ar+ precursor cell to differentiate to a T8+γ+ar− suppressor‐effector cell. A similar T suppressor‐effector cell can also be isolated directly from peripheral blood of normal donors.
Accessory function of human tumor cell lines I Production of interleukin 1 by the human histiocytic lymphoma cell line U‐937
Authors: Palacios Ronald , Ivhed Irene , Sideras Paschalis , Nilsson Kenneth , Sugawara Isamu , Fernandez Carmen
Published: February 2007

The established human histiocytic lymphoma cell line U‐937 spontaneously produced a factor with biological activity similar to that ascribed to interleukin 1 (IL1). Actually, supernatants from U‐937 cells promoted proliferation of thymocytes initiated by concanavalin A (Con A) and replaced the requirement of accessory cells for activation of highly purified circulating T lymphocytes induced by Con A. Phorbol myristate acetate (PMA) significantly increased the titers of the helper factor produced by U‐937 cells as compared to that secreted by non‐PMA‐treated U‐937 cells or PMA‐stimulated P388D1 murine macrophage tumor cells. Generally U‐937 cells did not secrete detectable IL1 activity during the first 24‐48 h of culture. However, after this initial period the level of IL 1 activity increased and reached a maximum at 5‐6 days of culture. Finally, the helper factor released by U‐937 cells had an apparent mol. wt. of 12000‐15000 as determined by Sephadex G‐100 chromatography and lacked interleukin 2 activity as shown by its inability to support growth of IL 2‐addicted T cell lines. To our knowledge this is the first report of an established human cell line capable of producing ILL 1.
Surface markers of cloned human T cells with helper or suppressor activity on pokeweed mitogen‐driven B cell differentiation
Authors: Mingari Maria Cristina , Melioli Giovanni , Moretta Alessandro , Pantaleo Giuseppe , Moretta Lorenzo
Published: February 2007

Human spleen T cells stimulated with pokeweed mitogen (PWM) were cloned under limiting conditions in microculture systems using interleukin 2 and irradiated autologous cells. Clones were screened for helper or suppressor activity on PWM‐dependent B cell differentiation by adding cell aliquots to either isolated B cells and PWM or to mixtures of T and B cells and PWM. Out of 97 clones tested, 14 promoted intense B cell differentiation, as assessed by measurements of secreted IgG, and 6 strongly inhibited B cell maturation induced by spleen T cells.

All the selected clones maintained their original activity after shortterm clonal expansion; in addition, a similar (helper or suppressor) effect was detected when the total number of plasma cells per well was evaluated. Suppressor clones had no cytolytic activity on autologous T and B cell blasts, K562 cells or antibody‐coated L 1210 mouse cells. Nine helper and 6 suppressor clones were analyzed for a battery of surface markers. All the clones were E rosette‐positive and expressed HLA‐DR (Ia) antigens. Fcμ eptor was present on a single helper clone, whereas Fcγ receptor was expressed on a suppressor clone only. All but two clones expressed the OKT4+/ OKT8−, a single suppressor clone was OKT8+/OKT4−, whereas coexpression of OKT4 and OKT8 antigens was detected in one helper clone. Thus, the claim that helper T cells are OKT4+/OKT8− and suppressor T cells are OKT4−/OKT8+ is not supported by the analysis of their phenotype at the clonal level.
Cross‐blocking studies with monoclonal antibodies against I‐A molecules of haplotypes b, d and k
Authors: Koch Norbert , Hämmerling Günter J. , Tada Nobuhiko , Kimura Shoji , Hämmerling Ulrich
Published: February 2007

For assessment of the distribution of allodeterminants on I‐A molecules, binding inhibition studies were performed with monoclonal anti‐I‐A antibodies (mAb) in which pairs of labeled and unlabeled mAb were tested for cross‐blocking on spleen cells of H‐2 haplotypes b, d and k. The data suggest that allodeterminants are randomly distributed on the surface of the I‐A molecule. Comparison of mAb with cross‐reactivity for b, d or k haplotypes indicates that the allelic forms of determinants are located in analogous positions on different I‐A antigens.
Effects of anti‐Ig reagents on T cell functions I. Activation of rabbit T cells by anti‐allotype antibodies
Authors: Vaeck Mark , de Smet Walter , Hamers Raymond , de Baetselier Patrick
Published: February 2007

Rabbit lymphocytes were analyzed by flow microfluorometry, using anti‐T cell and anti‐Ig reagents. Rabbit T cells and cells expressing surface Ig (B cells) appeared to belong to distinct subpopulations which could be separated on the basis of their selective adherence to nylon wool columns or to anti‐Ig‐coated dishes. Using flow microfluorometry, no evidence was obtained for the expression of a allotypes (VH framework) on T cells.

Separated lymphocyte populations were functionally characterized using an in vitro proliferation assay. B and T cells from rabbit spleen or peripheral blood responded in a differential fashion to B and T cell‐specific mitogens and to anti‐Ig antibodies. Although such T cells did not respond upon stimulation with anti‐Ig antibodies alone, significant proliferation could be induced by simultaneous addition of anti‐Ig and T cell growth factor. In addition, activated T cells, derived from lymph nodes of immunized rabbits, generated a proliferative response upon stimulation with anti‐Ig reagents alone. The above‐mentioned effects on T cells could be obtained using heterologous anti‐Ig antibodies or isologous anti‐allotype antibodies, directed either against a allotypes (VH framework) or against b allotypes (kappa light chain). Antibodies against the Fc portion of rabbit Ig or against irrelevant allotypic specificities were ineffective in triggering T cells. Fab fragments from anti‐allotype antibodies were equally stimulatory for T cells as compared to intact IgG, indicating that cross‐linking of Ig‐like molecules is not a necessary requirement for anti‐Ig‐induced T cell activation.
Alloactivated long‐term cultured human T lymphocytes express both HLA‐DR and SB antigens but lack lymphocyte stimulation capacity
Authors: Pawelec Graham , Blaurock Mathias , Schneider E. Marion , Shaw Stephen , Wernet Peter
Published: February 2007

Cell populations obtained from mixed leukocyte cultures of 6‐ or 10‐day duration were found specifically to restimulate primed lymphocytes detecting HLA‐linked SB as well as HLA‐D‐associated antigens. After expansion in vitro (9‐75 days) with medium containing interleukin 2, the cultured cells expressed the T lymphocyte markers detected in indirect immunofluorescence by monoclonal antibodies Lyt‐3, OKT3, OKT4, OKT8, and had high levels of HLA‐DR antigens. In addition, they were shown in cell‐mediated lymphocytotoxicity specifically to express SB antigens of the donor B cell type. Despite their positivity for DR and SB antigens, such cultured T cells failed to restimulate either SB‐ or D‐specific secondary lymphocyte proliferation. Homogeneous cloned populations of cultured T cells also lacked lymphocyte stimulation capacity. In contrast, B cell lines, which also expressed DR and SB antigens, were potent stimulators of both SB‐ or D‐directed proliferation. These data show that the activated T lymphocytes which express both HLA‐DR and SB antigens are by themselves unable to stimulate lymphocyte proliferation.
Clearance of interleukin 2 from the blood of normal and T cell‐depleted mice
Authors: Mühlradt Peter F. , Opitz Hans Georg
Published: February 2007

Partially purified, concentrated interleukin 2 (IL2) was injected i.v. into normal and T cell‐depleted mice. At various times after injection IL 2 was determined in the sera of these mice. An interference with the test by a potential inhibitor of IL 2 in the serum was excluded. IL 2 was cleared equally rapidly, with a half‐life of 3 min, from the blood of both groups of mice. It is concluded that IL 2 is a short‐range mediator under physiological conditions, and that clearance was not due to adsorption to T cells.
Murine genotype influences the in vitro production of γ (immune) interferon
Authors: Virelizier Jean‐Louis
Published: February 2007

Spleen cells from mice of 6 different strains were stimulated with pokeweed mitogen and the amount of γ interferon in the supernatants was measured. Three strains (BALB/c, A/J and C3H/He) were found to be low producers (less than 50 units) whereas three other strains (C57BL6, CBA and AKR) were high producers (50 to 500 units). F1 hybrids between a low producer strain (A/J) and a high producer strain (C57BL6) were found to produce low amounts of interferon. Nude mice did not produce detectable amounts of pokeweed mitogen‐induced γ interferon. The level of production of this T cell lymphokine is thus under genetic control.
The genetic basis of antibody production: The dominant anti‐arsonate idiotype response of the strain a mouse
Authors: Siekevitz Miriam , Gefter Malcolm L. , Brodeur Peter , Riblet Roy , Marshak‐Rothstein Ann
Published: February 2007

Immunization of the A strain of mice with the hapten p‐azophenylarsonate (Ars) results in an immune response in which approximately 50% of the anti‐Ars antibodies share cross‐reactive idiotypic determinants (IdCR). A gene or genes linked to the heavy chain constant region locus is required for the production of this idiotype. The expressed VH gene from a hybridoma cell line which expresses the IdCR has been cloned. DNA hybridization studies utilizing the VH gene have revealed that there are many related genes in both idiotype‐producing and idiotype‐nonproducing strains of mice. However, under stringent hybridization conditions, only a single band of 6.4 kb is present in Eco R1‐digested A strain DNA. Strains of mice which are phenotypically idiotype‐negative either lack this band completely or possess a much weaker one at this position. Utilizing DNA from Igh recombinant strains of mice, it has been shown that the VH locus controlling idiotype expression contains the structural gene information for the idiotype‐positive heavy chains. It has also been shown that DNA at this locus appears to be sufficient for the production of the cross‐reactive idiotype. Utilizing a DNA probe derived from regions flanking the structural gene has confirmed the relatedness of V genes in a variety of mouse strains and revealed a significant degree of polymorphism at the Igh locus.
The role of accessory cells in polyclonal T cell activation. I. Both induction of interleukin 2 production and of interleukin 2 responsiveness by concanavalin A are accessory cell dependent
Authors: Hünig Thomas , Loos Michael , Schimpl Anneliese
Published: February 2007

Recent studies from other laboratories have shown that concanavalin A (Con A) acts at two separate steps in polyclonal T cell activation: interleukin 2 (IL2) production, and induction of responsiveness to IL2. Using a combination of techniques for the depletion of accessory cells from lymph node T cells, we have investigated which of these steps, if not both, is responsible for the known requirement for accessory cells in the Con A response. It was found that with increasing T cell purification, first the ability is lost to produce sufficient levels of endogenous IL2, whereas induction of IL2 responsiveness can still take place. Further removal of accessory cells however yields a population of resting T cells that cannot be induced by Con A to become IL2‐reactive. It was concluded that both IL2 production and induction of reactivity to IL 2 are accessory cell‐dependent events.
Modulation of B and T cell subsets in mice treated with fractionated total lymphoid irradiation. II. Tolerance susceptibility of B cell subsets
Authors: Zan‐Bar Israel
Published: February 2007

Total lymphoid irradiation (TLI) results in long‐lasting changes in the characteristics of both T and B cells suggestive of arrested maturation. A characteristic feature of immature B cells is their high susceptibility to tolerance induction. This study examines the susceptibility to tolerance to bovine serum albumin (BSA) of TLI‐treated mice. Two experimental protocols were designed. In the first, tolerance to BSA was induced in TLI‐treated adult (BALB/c × C57BL/6)F1 mice, and the ability of B cells of those mice to respond to BSA was assessed in an adoptive transfer system. In the second experimental protocol, tolerance was induced in adoptive hosts reconstituted with purified B cells originating from TLI‐treated mice and with splenic T cells of normal, untreated mice. Results obtained in these two systems clearly demonstrated that splenic B cells of TLI‐treated mice are highly susceptible to tolerance induction. This high susceptibility of B cells is linked neither with the elevation of immature T cells nor with induced T suppressor cells which arise due to the long‐term malfunction of the thymus. Tolerance could be induced in TLI cells even 4 months after termination of the treatment. Thus, maturation processes of B cells in TLI‐treated mice are arrested for long periods of time.