Publications

A 34-year-old man presented with pulmonary aspergillosis on the 75th day after marrow transplant for chronic myelogenous leukemia. The patient had smoked marijuana heavily for several weeks prior to admission. Cultures of the marijuana revealed Aspergillus fumigatus with morphology and growth characteristics identical to the organism grown from open lung biopsy specimen. Despite aggressive antifungal therapy, the patient died with disseminated disease. Physicians should be aware of this potentially lethal complication of marijuana use in compromised hosts.

The cellular origin of hepatic collagen is under active investigation. Several recent studies using cells in primary culture suggest that hepatocytes are the source of much of the collagen in normal rat liver. In view of other data indicating that lipocytes produce substantial amounts of this protein, we have reexamined collagen biosynthesis in hepatocyte cultures that have been carefully characterized with respect to the presence of lipocytes. We find that routinely prepared hepatocyte isolates contain, by number, approximately 10% lipocytes. Lipocytes in early culture are difficult to visualize by phase-contrast microscopy but after 4 d proliferate and eventually replace the parenchymal cells. The size of the lipocyte subpopulation in these cultures correlates positively with collagen production. Similarly, removal of lipocytes by further processing of the initial hepatocyte isolate significantly reduces collagen production. Moreover, the only cells within hepatocyte cultures that display type I collagen by immunohistochemistry are lipocytes. We conclude that lipocytes are the principal source of collagen in primary hepatocyte cultures. The findings indicate also that these cells are the previously described "fibroblast" that appear in relatively long-term hepatocyte cultures.

Human-human B cell hybridomas constructed from B lymphocytes of common variable immunodeficiency (CVI) patients and the nonsecreting cell line WIL2/729 HF consistently secrete low levels of Ig and appear to retain a defect characteristic of the CVI patient's B cells. We assessed the differentiative capacity of retinoic acid (RA) on these hybridomas, as well as on hybridomas constructed from normal B cells and from patients with selective IgA deficiency. RA at concentrations varying between 10(-5) and 10(-9) M augmented IgM secretion 4-20-fold from four of four CVI hybridomas tested, but did not affect Ig secretion from normal or IgA-deficiency hybridomas. In support of this elevated Ig secretion, RA enhanced the de novo synthesis of biosynthetically labeled light (kappa) and heavy (mu) Ig (up to 4- and 15-fold, respectively) in the CVI hybridoma line JK32.1. The increase in IgM synthesis/secretion could not be accounted for by RA-induced alteration in the cell cycle. In inducing this increase in IgM production, RA was found to affect two aspects of Ig gene expression: (a) the steady-state levels of heavy and light chain mRNAs were enhanced, and (b) the processing of mu heavy chain transcripts to the secreted mRNA form became favored over the membrane mRNA form. We also show that expression of Leu-17 (CD38), a surface marker that is re-expressed in the late pre-plasma stage of B cell development, was increased by RA from less than 20% to greater than 90% of the total cell population, with a concomitant 4-10-fold augmentation in the mean fluorescence intensity. Changes in both Leu-17 expression and de novo Ig synthesis were prominent by 24 h, but could be observed as early as 8 h after induction. Taken together, our study demonstrates that RA affects a marked alteration in the differentiated state of the CVI hybridoma clones. This finding suggests that retinoids can enhance the functional capabilities of B cells with defects in maturation and support further studies to evaluate their clinical potential in CVI.