The pivotal role played by antigen in the clonal selection of B cells for initial participation in an immune response is well established. Antigen selective mechanisms ensure that antigen-binding antibodies are produced during all stages of the immune response. However, antibodies that lack specificity for the immunogen might also be produced during the course of an antigen-driven immune respon...

The specificity of recognition of H-2 antigens by various subsets of Tc cells was investigated with respect to the two separate molecules known to be coded in the H-2D(d) region (a) D which carries the private specificity H-2.4 and (b) D'which carries the public specificity H-2.28. BALB/c.H-2(db) mutant mice express D but not D' on their cell surfaces, whereas wild-type BALB/c mice express both...

The adaptive immune system constantly remodels its lymphocyte repertoire for better protection against future pathogens. Its ability to improve antigen recognition on the fly relies somatic mutation and selective expansion of B lymphocytes expressing high-affinity receptors. However, this rapid evolution inside an individual appears ineffective, hitting a modest ceiling antigen-binding affinity...

In order to test whether autoimmune hemolytic anemia in a patient with chronic lymphocytic leukemia was due to autoantibody production by the neoplastic clone, somatic cell hybrids were constructed between the patient's leukemic cells and a mouse myeloma line. Light-chain-restricted human immunoglobulin was secreted by 4 of 11 of the established hybrid lines. No binding of this immunoglobulin t...

We present seven cases of mantle cell lymphoma with morphological features of marginal-zone lymphoma. Of particular interest, four of the patients had predominant involvement of the gastrointestinal tract. All cases displayed the translocation t(11;14)(q13;q32) and expressed cyclin D1. Cytogenetic analysis revealed trisomy 3 in one case and somatic hypermutation of immunoglobulin heavy genes co...

In the immune system, many tolerance checkpoints exist to prevent self-antigens from stimulating the relentless growth of self-reactive B and T lymphocytes. The genes and molecular pathways underpinning these checkpoints overlap with those involved in tumor suppression. As with an inherited predisposition to cancer, inherited defects in self-tolerance genes typically precipitate autoimmune dise...

The typical cases have faint surface IgM/IgD expression with k/l light chain restriction; pan-B antigens are positive, but CD22 expression is weak. CD5 and CD23 test positive, whereas CD10 and FMC7 are negative; the expression of CD11c and CD25 is variable; the postulated normal counterpart is a peripheral CD5+/CD23+ B cell; based on the presence/absence of the CD38 antigen, a distinction was s...

Plant tissue culture is an alternative method of commercial propagation and is being used widely for the commercial propagation of a large number of plant species, including many medicinal plants. Somatic embryogenesis is a process by which asexual or somatic cells are induced to form embryos in culture. Somatic embryogenesis is a multi-step regeneration process starting with formation of pro-e...

Induction of somatic embryogenesis in absence of exogenous auxin can clarify some basic concepts of somatic embryogenesis.  Explants from leaf and petiole of Cucumber (Cucumis sativus) were used in this experiment for somatic embryogenesis using three different modified B5 basal media; boron and 2,4-D but no IAA as control (I), boron and IAA but no 2,4-D (II) and no boron, 2,4-D and IAA (III). ...