The heterogeneity of human Gc-globulin.

Gc-globulin or group-specific component, also known as the vitamin D-binding protein, was investigated by the combined use of electrofocusing and immunofixation. Serum of the Gc 2-2 type was found to contain a single protein band whereas serum of the Gc 1-1 type shows two bands with a lower isoelectric point. The Gc 1-2 type contains all three bands known as Gc-2 (pI 5.10), Gc-1Slow (pI 5.03), and Gc-1Fast (pI 4.95). Each apoprotein shows an anodal shift of about 0.07 pH unit after incubation with an excess of 25-hydroxycholecalciferol. After treatment with sialidase Gc-1Fast focuses in the position of Gc-1Slow, whereas the position of Gc-2 remains unchanged.     

The accumulation of immunoglobulins in the human tonsil.

The concentration of 5 types of immunoglobulins in both serum and the faucial tonsil was determined. The level for all types was significantly higher in the tonsil. IgG was detected as the main immunoglobulin in the tonsil, while the concentration of the other types was in about the same range. With the shortening of the biological half-live the accumulation index increases. The results give evidence for the antibody formation in the tonsil.     

The heterogeneity of mast cell tryptase from human lung and skin.

There has long been conjecture over the degree to which there may be structural and functional heterogeneity in the tetrameric serine protease tryptase (EC 3.4.21.59), a major mediator of allergic inflammation. We have applied 2D gel electrophoresis to analyze the extent, nature, and variability of this heterogeneity in lysates of mast cells isolated from lung and skin, and in preparations of purified tryptase. Gels were silver stained, or the proteins transferred to nitrocellulose blots and probed with either tryptase-specific monoclonal antibodies or various lectins. Tryptase was the major protein constituent in mast cell lysates, and presented as an array of 9-12 diffuse immunoreactive spots with molecular masses ranging from 29 to 40 kDa, and pI values from 5.1 to 6.3. Although the patterns obtained for lung and skin tryptase were broadly similar, differences were observed between tissues and between individual donors. Lectin binding studies indicated the presence of mono-antennary or bi-antennary complex-type oligosaccharide with varying degrees of sialylation. Deglycosylation with protein-N-glycosidase F (PNGase F) reduced the size of both lung and skin tryptase, while incubation with PNGase F or neuraminidase narrowed the pI range, indicating variable degrees of glycosylation as a major contributor to the size and charge heterogeneity. Comparison of different purified preparations of lung and skin tryptase revealed no significant difference in pH profiles, but differences were seen in reactivity towards a range of chromogenic substrates, with substantial differences in Km, kcat and degree of cooperativity. Mathematical modeling indicated that the variety in kinetics parameters could not result solely from the sum of varying amounts of isoforms obeying Michaelis-Menten kinetics but with different values of Km and kcat. The heterogeneity demonstrated for tryptase in these studies suggests that there are important differences in tryptase function in different tissues.     

Intramolecular base composition heterogeneity of human DNA.

The intramolecular base composition heterogeneity of human DNA has been investigated by electron microscopic observations of partially denatured structures and by equilibrium solution thermal denaturation techniques. DNA sequences having an average length of less than 2000 base pairs are found to be heterogeneous in base composition. These heterogeneous sequences occupy a minimum of 67 to 81% of the human genome.     

Fc-receptor heterogeneity of human suppressor T cells.

Concanavalin A (Con A) stimulated the IgM-binding subpopulation of human T cells (TM) to suppress the pokeweed mitogen-induced differentiation of B lymphocytes to plasma cells. Control TM cells that had not been Con A activated did not suppress. The degree of suppression was related to the number of Con A-TM cells added to the cultures and it was abolished by irradiation of the T lymphocytes either before or after the 24-hr culture period with Con A. Suppression did not require the presence of TG cells, whose suppressor potential has been previously established. These findings indicate that suppressor activity is not confined to the TG subpopulation but may be expressed by TM cells also.     

Functional heterogeneity of polyphosphoinositides in human erythrocytes.

After labelling of erythrocytes with [32P]P1 for 23 h, the specific radioactivities of the phosphomonoester groups of PtdIns4P and of PtdIns(4,5)P2 approached equilibrium values which were close to that of the gamma-phosphate of ATP (78-85%), showing that almost all of these phosphate groups were metabolically active. Phosphoinositidase C (PIC) activation, using Ca2+ and the ionophore A23187, of 32P-prelabelled erythrocytes was used to investigate a possible functional heterogeneity of the phosphoinositides. Hydrolysis of PtdIns(4,5)P2, measured from its radioactivity, decreased as function of the time of prelabelling up to a constant value equal to that measured from its content. In contrast, hydrolysis of PtdIns4P, determined both from radioactivity and from content, was always the same. These data suggest that newly labelled molecules of PtdIns(4,5)P2, initially accessible to PIC, then moved towards a PIC-resistant pool. This was further confirmed by measuring the fraction of labelled PtdIns(4,5)P2 molecules accessible to PIC after a prelabelling period of 5 min and different times of reincubation. Hydrolysis by PIC was also measured in erythrocytes in which the phosphoinositide content had been modified by activation (Mg2+-enriched cells) or inhibition (ATP-depleted cells) of the phosphoinositide kinases. The sizes of the PIC-resistant pools of polyphosphoinositides were not affected by these treatments, indicating that the kinases (and the phosphatases) act on the PIC-sensitive pools. This was also shown by the decrease in the production of Ins(1,4,5)P3 upon PIC activation in ATP-depleted erythrocytes. A model is presented in which the PIC-sensitive pools of polyphosphoinositides are those which are accessible to the kinases and the phosphatases and are rapidly turned over.     

人免疫球蛋白中肠道病毒71型中和抗体效价的测定

采用经典微量细胞病变法,应用近两年分离自中国手足口病(HFMD)高发区的3株肠道病毒71型(EV71)病毒株,对中国不同血液制品厂家生产的35批人免疫球蛋白制品进行抗-EV71中和效价检测。结果显示,3株不同EV71病毒株间的抗-EV71中和效价差异均在4倍以内,差异无显著的统计学意义(F=2.323,P0.05)。根据这3株毒株检测结果判定,35批人免疫球蛋白的抗-EV71均为阳性,肌肉注射用免疫球蛋白(简称肌丙)的抗-EV71-GMTs(525.9)显著高于静脉注射用免疫球蛋白(简称静丙)的GMTs(252.3,F=66.518,P0.01)。30批静丙的抗-EV71-GMTs中和效价分布在128.0~384.0之间。应开展原料血浆中抗-EV71中和效价的筛选,研制高效价的EV71特异性免疫球蛋白制品,用于HFMD的治疗和预防。