Hereditary stomatocytosis: phenotypical expression of sodium transport and band 7 peptides in 44 cases

The clinical heterogeneity and the role of red cell membrane protein band 7 in membrane transport were studied in 44 patients with hereditary stomatocytosis with normal red cell membrane lipids. These patients were arbitrarily categorized into three phenotypes, based on the extent of sodium influx: hereditary stomatocytosis Type I: with markedly increased Na influx (8.90 +/- 3.39 mmol/lRBC/h); Type II: with moderately increased Na influx (2.10 +/- 0.79) and Type III with normal Na influx (1.31 +/- 0.13). The three groups of patients were compared with normal controls (1.29 +/- 0.14). The extent of anaemia and jaundice was almost identical in the three groups in the presence of nearly the same degree of stomatocytosis (I: 54.8 +/- 10.7%, II: 38.8 +/- 12.8, and III: 40.2 +/- 10.8). Approximately one third of the cases (14/44) with hereditary stomatocytosis showed no overt haemolysis even with marked stomatocytosis. Cell hydration was abnormal in Type I (MCV 119.6 +/- 8.5 fl, MCHC 29.3 +/- 1.8%) but normal in Types II and III (MCV 98.2 +/- 11.7, 94.1 +/- 8.5; MCHC 34.4 +/- 2.1, 34.5 +/- 2.2). These results indicate that there was no correlation between the extent of Na influx and either the degree of stomatocytosis or the extent of overt haemolysis. The role of band 7 in membrane transport was also studied. Three components (30 kD, 28 kD and 26 kD polypeptides) of band 7 were analysed by SDS-PAGE and NEPHGE/SDS-PAGE, and the content of these polypeptides were expressed as the ratio to band 5. The 30 kDa polypeptide in the three groups was nearly identical to that in normal controls (12.3 +/- 4.0), except for non-haemolysing patients in Type II. The 28 kD peptide was also decreased in five out of nine cases of Type II (25.7 +/- 5.6) as compared with normal controls (32.9 +/- 3.6) and cases of Type I (35.8 +/- 2.8) and Type III (32.7 +/- 2.9). No deficiency of this peptide was noted in Type I patients. No correlation was observed between the content of the 28 kD polypeptide and Na influx (r = 0.416), but the 26 kD polypeptide tended to be elevated in cases with overt haemolysis. These results suggest that band 7 may not be essentially involved in the formation of stomatocytic changes, although the presence of subtle defects in band 7 structure and function may not be ruled out. The present findings provide an important starting point to initiate further extensive investigations.     

Effects of long-term acidification of extracellular pH on ATP-induced calcium mobilization in rabbit lens epithelial cells

ATP-induced calcium (Ca2+) mobilization was investigated in rabbit lens epithelial cells that had been cultured in a medium with pH of 7.4 (group 1), 7.2 (group 2), or 7.0 (group 3) for 10 to 21 d. Intracellular free Ca2+ ([Ca2+]i and pH (pHi) were measured by using fluorescent dyes, fura-2 and BCECF, respectively. The long-term acidification decreased the pHi to 7.15 +/- 0.01, from 7.22 +/- 0.01, in group 2 and to 7.09 +/- 0.01 in group 3. The administration of 10 micromol/l ATP produced an initial peak followed by a sustained increase in [Ca2+]i in the lens cells of group 1. Both the initial peak and the sustained increase in [Ca2+]i were enhanced in groups 2 and 3. The initial peak was abolished by pretreatment with 1 micromol/l thapsigargin, an ER Ca2+ pump inhibitor, but was not affected by the removal of extracellular Ca2+. On the other hand, the sustained increase was suppressed either by the thapsigargin treatment or by the Ca2+ removal. Treatment with only thapsigargin caused a sustained increase in [Ca2+]i that was greater in group 3 than in group 1. These results suggest that (1) the ATP-induced initial peak in [Ca2+]i is due to Ca2+ release from the intracellular stores, (2) the sustained increase in [Ca2+]i is mediated through either Ca2+ influx from the extracellular space or Ca2+ release from the store triggered by the Ca2+ influx, and (3) long-term, moderate acidification enhances both the initial peak and the sustained increase in [Ca2+)]i in rabbit lens epithelial cells. One possible mechanism of the ATP-induced Ca2+ influx seems to be a capacitative Ca2+ entry pathway.     

Cellular biological differences between human myeloma cell lines KMS-12-PE and KMS-12-BM established from a single patient

To clarify cellular biological varieties of myeloma cells, biological differences were analyzed between 2 human myeloma cell lines, KMS-12-PE and KMS-12-BM, derived from pleural effusion and bone marrow, respectively, of a single patient. Although both lines were considered to be derived from the same clone because both had the same chromosomal marker and immunoglobulin H rearrangement, several biological differences were noted. CD11a and CD20 were highly expressed in the KMS-12-BM line, whereas the KMS-12-PE line showed a higher expression of CD7 and CD95/Fas. Although growth was stimulated in KMS-12-BM by interleukin-6 and interferon-alpha, it was inhibited in KMS-12-PE. In addition, apoptosis inhibitors Bcl-2 and Bcl-X(L) were highly expressed in KMS-12-BM cells. Because KMS-12-PE was cultivated 2 months before KMS-12-BM, these differences might be related to their origin (pleural effusion and bone marrow) or the phases of disease progression. However, these biological differences may help clarify myeloma cell biology and lead to improvement in treatment for myeloma patients.