Biomedical subjects

Karel Drbal

Publications and source records attributed to Karel Drbal.

6 recordsLinked to original sources

PubMed2006

Different role for mouse and human CD3delta/epsilon heterodimer in preT cell receptor (preTCR) function: human CD3delta/epsilon heterodimer restores the defective preTCR function in CD3gamma- and CD3gammadelta-deficient mice.

The majority of T cell receptor (TCR) complexes in mice and humans consist of a heterodimer of polymorphic TCRalpha and beta chains along with invariant CD3gamma, delta, epsilon, and zeta chains. CD3 chains are present as CD3gammaepsilon, deltaepsilon, and zetazeta dimers in the receptor complex and play critical roles in the antigen receptor assembly, transport to the cell surface, and the receptor-mediated signal transduction. That CD3 chains play critical roles in thymocyte development is apparent from the analyses of CD3 deficient mice. PreT cell receptor (preTCR)-mediated CD4(-)CD8(-) (double negative or DN) to CD4(+)CD8(+) (double positive or DP) transition is severely impaired in mice deficient in either CD3gamma, or epsilon, or zeta chain. In contrast, CD3delta deficiency impairs thymocyte maturation at the CD4(+)CD8(+) double positive (DP) stage suggesting that CD3delta is not required for the preTCR-mediated DN to DP transition. However, recent data suggest that a defect in human CD3delta results in impaired development at the DN stage indicating a role for hCD3delta in preTCR-mediated DN to DP transition. To determine if human CD3delta/epsilon (hCD3delta/epsilon) could mediate preTCR-mediated DN to DP transition, we employed a human CD3 transgene that encodes full length CD3delta and a truncated but functional form of CD3epsilon. Surprisingly, the transgene restored the defective preTCR function in not only CD3epsilon- but CD3gamma- and CD3gammadelta-deficient mice as well. A possible role for human CD3delta/epsilon heterodimer in the preTCR-mediated DN to DP transition is discussed.

Animals↗

PubMed2005

The HLDA8 blind panel: findings and conclusions.

There were over 600 antibodies submitted to HLDA8, with many of unknown specificity. Of these, 101 antibodies were selected for a blind panel study that also included 5 negative controls and 27 positive controls of known CD specificity making a total of 133 antibodies in the final panel. Of the 101 unknowns, 31 antibodies were identified during the course of this blind panel study as being specific for known molecules and included some specific for MHC class II antigens, CD45 isoforms and the Dombrock antigen. Several antibody pairs among those in the blind panel were found to have very similar staining patterns and were therefore compared by immunohistochemical and/or Western blot analyses for identity.

Antibodies↗

PubMed2005

CD molecules 2005: human cell differentiation molecules.

The immune system works through leukocytes interacting with each other, with other cells, with tissue matrices, with infectious agents, and with other antigens. These interactions are mediated by cell-surface glycoproteins and glycolipids. Antibodies against these leukocyte molecules have provided powerful tools for analysis of their structure, function, and distribution. Antibodies have been used widely in hematology, immunology, and pathology, and in research, diagnosis, and therapy. The associated CD nomenclature is commonly used when referring to leukocyte surface molecules and antibodies against them. It provides an essential classification for diagnostic and therapeutic purposes. The most recent (8th) Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA), held in Adelaide, Australia, in December 2004, allocated 95 new CD designations and made radical changes to its aims and future operational strategy in order to maintain its relevance to modern human biology and clinical practice.

Antigens, CD↗

PubMed2003

Selective inhibition of T cell activation via CD147 through novel modulation of lipid rafts.

The plasma membrane is compartmentalized into microdomains and the association/dissociation of receptors and signaling molecules with/from these membrane domains is a major principle for regulation of signal transduction. By following the reorganization of microdomains on living cells and performing biochemical studies, we show that Ab targeting of the T cell activation-associated Ag CD147 prevents TCR stimulation-dependent reorganization and clustering of microdomains. Triggering CD147 induces a displacement of the GPI-anchored coreceptors CD48 and CD59 from microdomains in human T lymphocytes. This perturbation of microdomains is accompanied by a selective inhibition of TCR-mediated T cell proliferation. The CD147-inhibited cells secret normal levels of IL-2 but acquire reduced amounts of the IL-2 receptor alpha-chain CD25. These results indicate that negative regulating signals can modulate microdomains and suggest a general mechanism for inhibition of receptor signaling.

Antibodies, Monoclonal↗

PubMed2003

A novel monoclonal reagent recognizing native and denatured Vbeta5.3-related chains of human T cell receptor.

Monoclonal antibodies to specific families of TCR variable domains serve as highly useful immunochemical tools for basic research in T-cell biology and diagnosis of autoimmune diseases. Monoclonal antibody MEM-262 characterized in this communication recognizes beta chains of the TCR expressed by HPB-ALL cell line (carrying Vbeta5.3) and a small subset of peripheral blood T cells. This subset is larger than that recognized by a previously described Vbeta5.3-specific mAb. MEM-262 potently stimulates selective expansion of the T-cell subset, efficiently immunoisolates native TCR complexes as well as free beta chains and uniquely recognizes denatured TCRbeta chains under the conditions of Western blotting.

Animals↗

PubMed2002

Engagement of Na,K-ATPase beta3 subunit by a specific mAb suppresses T and B lymphocyte activation.

In order to identify new molecules involved in regulation of T cell proliferation, we generated various mAb by immunization of mice with the T cell line Molt4. We found one mAb (termed P-3E10) that down-regulated the in vitro T cell proliferation induced by CD3-specific OKT3 mAb. The P-3E10 mAb was also able to inhibit IFN-gamma, IL-2, IL-4 and IL-10 production of OKT3-activated T cells. The antigen recognized by P-3E10 mAb is broadly expressed on all hematopoietic as well as on all non-hematopoietic cell lines tested so far. Within peripheral blood leukocytes, the P-3E10 antigen was detected on lymphocytes, monocytes and granulocytes. Human umbilical vein endothelial cells (HUVEC) also scored positively. By evaluating the effect of P-3E10 mAb on these cell types we found that it also inhibited anti-IgM-induced B cell proliferation. However, it did not block growth factor-mediated proliferation of HUVEC, and spontaneous proliferation of SupT-1, Jurkat, Molt4 and U937 cell lines. Moreover, it did not influence phagocytosis of human blood monocytes and granulocytes. Biochemical analysis revealed that the P-3E10 antigen is a protein with a mol. wt of 45-50 kDa under non-reducing and 50-55 kDa under reducing conditions. By using a retroviral cloning system, the P-3E10 antigen was cloned. Sequence analysis revealed the P-3E10 antigen to be identical to the beta3 subunit of the Na,K-ATPase.

Amino Acid Sequence↗