摘要:

The activity of leukocyte migration inhibitory factor (LIF) obtained from Sephadex‐G‐100‐chromatographed supernatants of concanavalin‐A‐stimulated human lymphocytes was suppressed by two synthetic serine esterase and serine protease inhibitors (di‐isopropylfluorophosphate (DFP) and phenylmethylsulfonyl fluoride (PMSF)). LIF activity was also reduced by the naturally occurring protease inhibitors soybean trypsin inhibitor and aprotinin. The observed effect of DFP and PMSF was irreversible, since elimination of the inhibitors by dialysis did not restore LIF activity. The effect of PMSF was dose‐, time‐, and temperature‐dependent, and hydrolytic products of PMSF as well as sodium fluoride were inactive in blocking LIF. These results suggest that LIF may act as a serine esterase or a serine protease, or both of these, and that this putative enzyme is present in an activated form in supernatants from mitogen‐stimulate

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1977.tb00327.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Previously reported experiments suggested that an esterase or a protease, or both, might participate in the expression of human leukocyte migration inhibitory factor (LIF). To clarify this further, a wide variety of simple esters were tested for the ability to protect LIF against inactivation by the serine esterase inhibitor phenylmethylsulfonyl fluoride (PMSF). α‐N‐benzoyl‐L‐arginine ethylester (BAEE), a typical trypsin substrate, and bis‐p‐nitrophenyl phosphate (BNPP); a phosphodiester, were the only esters capable of retaining LIF activity in the presence of PMSF. Agents chemically closely related to these esters were inactive. Moreover, the protection afforded by BAEE and BNPP was the kind that would be anticipated if the esters and irreversible inhibitor competed for the same site on LIF. BAEE and BNPP also protected against inactivation by di‐isopropyl‐fluorophosphate (DFP), another irreversible serine esterase inhibitor. In addition, LIF‐treated leukocytes partly escaped migration inhibition in the presence of BAEE and BNPP, respectively. These results indicate that human LIF contains a serine residue necessary for lymphokine activity. It is still not proved, however, that LIF as an enzyme is capable of hydrolyzing BAEE and BNPP, although it seems highly possible. The substrate specificities of a putative LIF enzyme are discussed on the basis of the chemical structur

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1977.tb00328.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Specific helper and suppressor cells were induced in vitro with low and high doses, respectively, of protein antigen in Marbrook cultures. On different days of culture the fells from helper and suppressor cultures were size‐fractionated by 1‐g velocity sedimentation and the different fractions tested for specific activity in secondary co‐operative cultures after challenge with protein‐hapten conjugate. We observed a change in the size distribution of both helper and suppressor cells during their in vitro differentiation; the first helper and suppressor cell to be detected is a large (blast) cell, whereas later both help and suppression is mediated by medium‐ and small‐sized lymphocytes. A difference between helper and suppressor cells with regard to their relative dependence on DNA synthesis and proliferation during their induction was also seen. Although both DNA synthesis and divisions are needed for the optimal generation of both types of cells, some suppressor activity was still induced in cultures treated with mitosis‐arresting concentrations of demecolcine (Colcemid®). Treatment of helper cell cultures with Colcemid or with 5‐bromodeoxyuridine plus light completely ab

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1977.tb00329.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

IgG from 13 anti‐A, 26 anti‐B, and 10 anti‐Duffy antisera were used to coat human erythrocytes. With antisera specific for each of the three VHsubgroups, VHI, VHII, and VHIII, a clear VHsubgroup restriction was shown in these antibody preparations. Of the 26 IgG anti‐B‐coated cell preparations, 21 were agglutinated exclusively by the anti‐VHIII antiserum, and 5 were agglutinated mainly by the anti‐VHIII antiserum but showed also some reactions using anti‐VHI or anti‐VHII antiserum, or both. Similarly, 11 out of the 13 IgG anti‐A antibodies belonged to VHI, and only 2 to VHIII. The 6 IgG anti‐Fy(a) antibodies were restricted to subgroups VHI and VHII, and of the 4 IgG anti‐Fy(b) antibodies, 3 belonged to subgroup VHIII and one to VHII. Additional experiments indicated that IgM anti‐A and IgM anti‐B antibodies showed the same type of restriction to VHsubgroups as the correspondin

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1977.tb00330.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Twelve different HLA antisera, detecting antigens of both A and B series and the superspecificities w4 and w6, were tested for platelet‐aggregating activity in 75 antiserum‐platelet combinations. The correlation between the HLA specificities of the antisera and the aggregating effect on platelets carrying the corresponding antigens was significant (P= 0.011). Because the platelet aggregation test is being used for screening of circulating immune complexes, falsely positive reactions caused by HLA antibodies must be eliminated by adequate control experime

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1977.tb00331.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY