Haemophiliac pseudotumour: two case reports of patients with moderate haemophilia A.

We report on two patients with haemophiliac pseudotumours who did not respond to intensified factor replacement therapy. Therefore the pseudotumours had to be removed surgically in both cases.

Divergent activities of protein kinases in IL-6-induced differentiation of a human B cell line.

Lymphokines including IL-2, IL-4, and IL-6 are involved in the induction of Ig production by activated B cells. We have investigated the role of protein kinases in IL-6-induced IgM secretion by SKW6.4 cells, an IL-6 responsive B cell line. IL-6-stimulated IgM production was inhibited by elevated intracellular cAMP induced either by the addition of dibutyryl cAMP or cholera toxin. The inhibitory effect of elevated intracellular cAMP was blocked by n-(2-(Methylamino)ethyl)-5-isoquinolinesulfonic dihydrochloride (H8), an inhibitor of protein kinase A. H8 did not affect IgM secretion induced by IL-6. In contrast, the addition of 1-(5-isoquinolinesulfonyl)-2-methylpiperizine dihydrochloride (H7), an inhibitor of protein kinase C activity, markedly inhibited IL-6-stimulated IgM production by SKW6.4 cells. H7 and elevated intracellular cAMP inhibited IgM mRNA expression and subsequent IgM synthesis by SKW6.4 cells. SKW6.4 proliferation, as determined by [3H]thymidine incorporation, was not markedly affected by IL-6, dibutyryl cAMP, cholera toxin, H7 or H8. PMA, an activator of protein kinase C, directly stimulated significant IgM secretion by SKW6.4 cells. When added to PMA-stimulated SKW6.4 cells, IL-6 stimulated additional IgM production. This observation suggested that IL-6 could stimulate differentiation without activating protein kinase C. This was confirmed by demonstrating that IL-6 did not stimulate production of diacylglycerol, did not induce the translocation of protein kinase C from the cytosolic compartment to the plasma membrane and could induce SKW6.4 cells to produce IgM after depletion of their cellular protein kinase C by PMA. Taken together these results suggests that IL-6-stimulated IgM production requires utilization of an H7-inhibitable protein kinase that can be inhibited by a protein kinase A-dependent pathway. Despite the fact that PMA can stimulate IgM production in SKW6.4 cells, IL-6 appears to use a protein kinase pathway other than protein kinase C to induce IgM production.

Chemical and immunological characteristics of four different L-asparaginase preparations.

We studied the differences in protein composition and immunologic reactivity of two E. coli-derived L-asparaginase (l-Asp) preparations (I and II), Erwinia-Asp (III) and PEG-modified E. coli l-Asp (IV). On gel filtration, each of preparations I-III showed three major peaks at 100, 270 and 460 KD, all with enzyme activity, whereas PEG-Asp showed peaks at 35 and 220 KD. On SDS-PAGE one major subunit could be identified at 32 KD (I and II) or 40 KD (III), whereas PEG-modified l-Asp could only be detected by lowering the polyacrylamide concentration and gave a single band above 200 KD. Using a polyclonal rabbit antibody generated against preparation I, only the E. coli l-Asp preparations (I and II) formed precipitin lines on Ouchterlony double diffusion. After freezing and thawing, preparation IV also reacted with this antibody. In sera from patients treated with preparation I, antibodies (detected by ELISA) reacted with preparations I and II but not with preparations III and IV. These results indicate that Erwinia-Asp (III) and PEG-Asp (IV) are distinct from E. coli preparations (I and II) by molecular weight and immunological behavior. They also provide an experimental rationale for the use of Erwinia-Asp as well as PEG-Asp in E. coli Asp-sensitized patients.

Elimination of l-asparaginase in children treated for acute lymphoblastic leukemia.

The elimination of l-asparaginase (l-Asp) was studied in 8 children treated for acute lymphoblastic leukemia according to the CoALL 82 protocol. The patients received four doses of l-Asp as a single agent during induction chemotherapy. We studied the elimination of l-Asp during the first infusion in 1 child, during the second in 3, during the third in 2 and during the forth in 2 children. Using Western blot technique and an experimental rabbit antibody to l-Asp, we were able to detect a single band at 32 kilodaltons (KD) in the serum of all patients between 4 and 36 h after infusion. The molecular weight remained unchanged and no other bands occurred during the time of observation. The detection limit of this method was calculated to 5 micrograms/ml using radial immunodiffusion. Incubation of l-Asp with pooled normal human serum caused no degradation of the enzyme during 48 h at 37 degrees C. Neither the total enzyme nor fragments were detectable in the urine of the patients collected during 8 h after l-Asp infusion. From these results we conclude that l-Asp is not cleaved by proteases in humans. The enzyme is most probably eliminated by the reticuloendothelial system.