Intracellular immunoglobulin G 'pseudocrystals' in a patient with chronic B-cell leukemia

Aggregates, crystals, gels, and amyloids: intracellular and extracellular phenotypes at the crossroads of immunoglobulin physicochemical property and cell physiology

Recombinant immunoglobulins comprise an important class of human therapeutics. Although specific immunoglobulins can be purposefully raised against desired antigen targets by various methods, identifying an immunoglobulin clone that simultaneously possesses potent therapeutic activities and desirable manufacturing-related attributes often turns out to be challenging. The variable domains of individual immunoglobulins primarily define the unique antigen specificities and binding affinities inherent to each clone. The primary sequence of the variable domains also specifies the unique physicochemical properties that modulate various aspects of individual immunoglobulin life cycle, starting from the biosynthetic steps in the endoplasmic reticulum, secretory pathway trafficking, secretion, and the fate in the extracellular space and in the endosome-lysosome system. Because of the diverse repertoire of immunoglobulin physicochemical properties, some immunoglobulin clones' intrinsic properties may manifest as intriguing cellular phenotypes, unusual solution behaviors, and serious pathologic outcomes that are of scientific and clinical importance. To gain renewed insights into identifying manufacturable therapeutic antibodies, this paper catalogs important intracellular and extracellular phenotypes induced by various subsets of immunoglobulin clones occupying different niches of diverse physicochemical repertoire space. Both intrinsic and extrinsic factors that make certain immunoglobulin clones desirable or undesirable for large-scale manufacturing and therapeutic use are summarized.

Ribosome-lamella complexes in the peripheral blood of patients with chronic lymphocytic leukemia are associated with serological immune deficiency

The ribosome-lamella complex (RLC) is a cylindrical structure composed of different numbers of circular lamellae with associated particles, regarded as ribosomes, around a central core. Structures resembling RLC, but lacking the typical mature appearance of RLC, have been called pre-RLC. The authors have found RLCs and pre-RLCs in peripheral lymphocytes of 3 patients with chronic lymphocytic leukemia (CLL). The fact that CLL patients with RLCs were in early Rai clinical stages, had good clinical prognostic factors, and did not require immediate therapy indicates that RLCs occurred in the early course of some cases of CLL. Moreover, the presence of RLC was associated with hypogammaglobulinemia M.

Intracytoplasmic filamentous inclusions in the peripheral blood of a patient with chronic lymphocytic leukemia. A bright-field, electron microscopic, immunofluorescent, and flow cytometric study

Intracellular inclusions in lymphoproliferative disorders are not common. Multiple different types of inclusions have been reported in chronic lymphocytic leukemia (CLL), including vacuoles, crystals, and pseudocrystals. Most of the reported cases were seen in the bone marrow lymphocytes, and the majority of these on electron microscopy. We report a case of long-standing CLL with no therapy that had filamentous cytoplasmic inclusions in the peripheral blood that were readily seen by light microscopy. Electron microscopy demonstrated dilated cisternae of the rough endoplasmic reticulum filled with amorphous electron-dense material. By immunofluorescence, the material proved to be immunoglobulin G-lambda deposits. The immunophenotype had the typical CLL pattern with positive staining with CD19, CD5, and CD23, and low-density CD20 staining; however, it also had unusual staining with CD25 and intermediate-intensity staining with CD22.