Interleukin-1 beta converting enzyme requires oligomerization for activity of processed forms in vivo.

Interleukin-1 beta converting enzyme (ICE) is composed of 10' (p10) and 20 kDa (p20) subunits, which are derived from a common 45 kDa precursor. Recent crystallographic studies have shown that ICE exists as a tetramer (p20/p10)2 in the crystal lattice. We provide evidence that the p10 and p20 subunits of ICE associate as oligomers in transfected COS cells.

A novel human protease similar to the interleukin-1 beta converting enzyme induces apoptosis in transfected cells.

We have identified a novel cDNA encoding a protein (named TX) with > 50% overall sequence identity with the interleukin-1 beta converting enzyme (ICE) and approximately 30% sequence identity with the ICE homologs NEDD-2/ICH-1L and CED-3. A computer homology model of TX was constructed based on the X-ray coordinates of the ICE crystal recently published. This model suggests that TX is a cysteine protease, with the P1 aspartic acid substrate specificity retained.

Influence of human leukocyte antigen genes on TCR V gene segment frequencies.

Human leukocyte antigen (HLA)-dependent selection mechanisms exerted during thymic maturation are supposed to be main contributing factors to the genetic predetermination of the TCR repertoire and may have a detectable effect on adult peripheral blood lymphocyte V segment frequencies. Here, we analyzed whether polymorphic or non-polymorphic HLA determinants are associated with selected expression of some V gene segment specificities. We first examined the reactivity of 17 V segment specific mAb on purified CD4+ and CD8+ cell fractions in 10 unrelated people.

TCR gene segments from at least one third of V alpha subfamilies rearrange at the delta locus.

Using PCR and an experimentally validated V alpha subfamily-specific oligonucleotide panel (V alpha 1-w29), we have investigated whether the TCR delta chain may increase its combinatorial diversity by using V genes considered as alpha chain-specific. We show that at least 10 distinct human V alpha segments rearrange at the J delta locus, leading to scrambling of the two V gene repertoires. Fifty-five per cent of the V alpha/J delta transcripts characterized here were in frame.

Limited T-cell receptor diversity in liver-infiltrating lymphocytes from patients with primary biliary cirrhosis.

Primary biliary cirrhosis is associated with the presence of high-titer anti-mitochondrial autoantibodies as well as T-cell infiltration of the liver, suggesting the involvement of autoimmune mechanisms. We have studied here the sequences of T-cell receptor alpha and beta chains expressed by T-cell clones derived from liver-infiltrating lymphocytes of two patients with primary biliary cirrhosis. Among the eight clones studied from the first patient, four expressed the same member of the V beta 6 subfamily, associated with either V alpha 4 (three clones) or V alpha 21 (one clone) gene segment.

Fine specificity of monoclonal antibodies directed at human T cell receptor variable regions: comparison with oligonucleotide-driven amplification for evaluation of V beta expression.

Seven distinct anti-human T cell receptor (TcR) V region monoclonal antibodies (mAb) were generated by immunizing mice with either human T cell lines or transfected murine cells expressing human TcR V beta genes. The specificity of these reagents was determined as follows: T cells recognized by each mAb were purified from the peripheral blood of healthy donors and TcR transcripts expressed in these cells were analyzed using oligonucleotide-driven amplification and cDNA sequencing. Four mAb were found to delineate the V beta 3, V beta 8, V beta 17 and V beta 19 subfamilies, respectively.

Analysis of T-cell receptor variability in transplanted patients with acute graft-versus-host disease.

T lymphocytes play a pivotal role in graft-versus-host disease (GVHD) and largely contribute to the graft-versus-leukemia (GVL) effect. Most mature T lymphocytes specifically recognize antigens through the alpha/beta T-cell receptor (TCR). Each alpha/beta TCR chain includes a constant region and a variable region, the latter being encoded by V-J alpha or V-D-J beta rearranged gene segments.

Differential regulation of voltage- and calcium-activated potassium channels in human B lymphocytes.

The expression and characteristics of K+ channels of human B lymphocytes were studied by using single and whole-cell patch-clamp recordings. They were gated by depolarization (voltage-gated potassium current, IKv, 11-20 pS) and by an increase in intracellular Ca2+ concentration (calcium-activated potassium current, IKCa, 26 pS), respectively. The level of expression of these channels was correlated with the activational status of the cell.

An experimentally validated panel of subfamily-specific oligonucleotide primers (V alpha 1-w29/V beta 1-w24) for the study of human T cell receptor variable V gene segment usage by polymerase chain reaction.

We report here the characterization of a series of T cell receptor (TcR) V alpha or V beta subfamily-specific oligonucleotide primers. Criteria that have guided the design of each oligonucleotide include appropriate thermodynamic parameters as well as differential base-pairing scores with related and unrelated target sequences. The specificity of the oligonucleotides for each V alpha or V beta subfamily was tested by polymerase chain reaction (PCR) on both a series of TcR encoding plasmid DNA and clonal T cell populations.

Human severe combined immunodeficiency disease: phenotypic and functional characteristics of peripheral B lymphocytes.

Human severe combined immunodeficiency disease (SCID) includes an X-chromosome-linked type characterized by a complete absence of mature T cells, hypogammaglobulinemia but normal or elevated number of B cells, suggesting that the disease results from a block in early T cell differentiation. It has been shown that B cells from obligate carrier women of this disorder exhibit the preferential use of the nonmutant X chromosome as the active X (as shown for T cells), suggesting that the SCID gene product has a direct effect on B cells as well as on T cells. To examine this question, we analyzed the phenotypic and functional characteristics of peripheral B cells from nine infants with SCID.

Further evidence for a human B cell activating factor distinct from IL-4.

Supernatants from activated human T cell clones were previously shown to contain B cell-activating factor (BCAF), an activity which results in polyclonal resting B cell stimulation. In the present study, we investigate the relationship between this activity and human interleukin-4 which was also shown to act on resting B cells. The supernatant of the T cell clone TT9 contains IL-4 but anti-IL-4 antiserum does not affect the response of B cells as measured by thymidine uptake or cell volume increase.

Human B cell activating factor (BCAF): production by a human T cell tumor line.

In a previous study, we demonstrated that supernatants from human T cell clones stimulated by a pair of anti-CD2 monoclonal antibodies cause resting human B cells to become activated and to proliferate in the absence of any other signals. The activity responsible for these effects was shown to be different from already characterized lymphokines and in particular from IL-2 and IL-4, and was named B Cell Activating Factor or BCAF. In this paper, we describe the production of BCAF by a human T cell tumor line T687 after phorbol myristate acetate (PMA) stimulation; this production can be potentiated by phytohemagglutinin (PHA).

Soluble mediators can replace helper T cells in the activation of resting B lymphocytes: evidence for a human B cell activating factor.

We were interested in studying the participation of T cell-derived soluble factors in the early steps of B cell activation. Thus supernatants containing such factors were obtained following activation of human T cell clones and their effects on isolated B cells investigated. These supernatants induced activation, blastogenesis and proliferation of purified resting human B cells.

Activation of resting human B cells by helper T-cell clone supernatant: characterization of a human B-cell-activating factor.

The effects of helper T-cell clone supernatants on resting human B cells were investigated. Four different helper T-cell clones (two T4+ and two T8+) were stimulated by anti-T3 monoclonal antibodies on Sepharose beads or anti-T11(2) plus anti-T11(3) monoclonal antibodies. The supernatants from these activated clones induced the proliferation of highly purified resting B lymphocytes from the peripheral blood.

Supernatant from a cloned helper T cell stimulates resting B cells to express transferrin and IL-2 receptors.

We describe the properties of the supernatant from a murine cloned helper T cell (clone 52.3) which is able to polyclonally activate most resting B cells in the absence of any additional stimulus. We hypothesize that an activity which we call BCAF (B-cell-activating factor(s] exists in our supernatant which can activate resting B cells alone or in conjunction with other lymphokines.

Lymphocyte activation by purified HLA-DR molecules fused into autochthonous "stimulating cells".

Affinity-purified Ia molecules derived from the Daudi cell line were reconstituted into vesicles with Sendai virus envelope glycoproteins. These vesicles inserted into human peripheral leukocytes could induce stimulation of autologous lymphocytes, as measured by thymidine uptake, 6 days later. It is suggested that this method could provide a means to study allostimulation at the molecular level.

Altered expression of heat shock proteins in embryonal carcinoma and mouse early embryonic cells.

In a previous paper, we have shown that in the absence of stress, mouse embryonal carcinoma cells, like mouse early embryo multipotent cells, synthesize high levels of 89- and 70-kilodalton heat shock proteins (HSP)(O. Bensaude and M. Morange, EMBO J.