- Email: [email protected]
An immunochemical explanation for the cynap phenomenon and for antihuman kappa Ig (AHG) augmented cytotoxicity (CDC)
Abstracts
29
MEMORY T L Y M P H O C Y T E SU.~J]IVAL IS ":EDIATED ZY FIZROZLAST$. J. Xurnick, S. Scott, F. Pandolfi, Department of Pathology, ~ A a s s a c h u s e { t ~ C e n e r a l llospital, Boston, MA. Ue report that a ,~]broblast produced factor can ollow the .~rolon~,ed survival oF activated IL-2 propagnt,bl T lybphocFtes in tI~,~ nbseT~, o ~ IT,-2 or antigenic stimulation. Uhen the activated ceils are remove4 from the presence of aatigen{e sti;m~li oz- p r o l i f e r a t i o n - i n d u c i n z cytokines (such as [L-2), they rapi,!] F cease ,',ividing and succu-~.h to apoptosis. .~owever, IT.-2 lep:~'n.].-
r e t a i n e d , and s u r v i v i n ' ~ c a l ] s r a a a i u e d s ) e c i f i c e v t o t o x i e a c t i v i t y . The r e s p o n s i b l e f a c t o r s have n o t v e t b e e n ] c ~ a n t i f i e d , b u t t ~ e a c t i v i t y of the FC~I is distinct £ron any o ~ the [nt,r]eukins I throulh 7. These results su<~cs~ an antigen non sr)<~cific ",mchn~{s t f(~r retention of activated "memory "~ lwphocyt~,s. The f[broblast source o~ this activity su:
AN IMMUNOCHEMICAL EXPLANATION FOR THE CYNAP PHENOMENON AND FOR ANTIHUMAN KAPPA Ig (AHG) AUGMENTED CYTOTOXICITY (CDC). T.C.Fuller,A.Fuller,M.Golden,S.Zakroff and G.E.Rodey. Mass. Gen. Hospital, Boston MA. and Emery University, Atlanta GA. HLA Class I alloantigens express multiple epitopes and human alloantibodies (aAb) have been identified against many of them. We have shown that individual aAb are nonreactive in standard CDC (CYNAP) but can be converted to direct C D C with the addition of AHG to C D C (Transplantation 34:24, 1982). The mechanisms for this phenomena have now been clarified by experiments using affinity-purified aAb, subclass specific @IgH, human Clq binding assays using an indirect sandwich assay and quantitation by flow cytometry. We have found that CYNAP reactions are not generally caused by low affinity or non-C fixing aAb [evidence: Fab and F(ab')2 HLA aAb are not augmented in AHG-CDC nor are antiIgH chain reagents effective with aAb; in fact, @-IgG(Fc) inhibits C D C due probably to steric blockage of C binding]. Use of single HLA aAb populations in conjunction with the AHG(kappa)-augmenting reagent results in a 200% to 400% increase in Clq binding over that when either reagent is used alone, thus demonstrating synergy of the reactants. These experiments indicate that two adjacent, noncompeting HLA aAb bound to spatially distinct epitopes on an HLA molecule, or a single HLA specific aAb in concert with the AHG binding to this HLA aAb, are required for efficient (bivalent) Clq binding and C-mediated lympholysis. In contrast, CYNAP is caused by the presence of a single population of aAb which cannot fix Clq bivalently and thus, cannot induce the subsequent cascade of C components.
29
MEMORY T L Y M P H O C Y T E SU.~J]IVAL IS ":EDIATED ZY FIZROZLAST$. J. Xurnick, S. Scott, F. Pandolfi, Department of Pathology, ~ A a s s a c h u s e { t ~ C e n e r a l llospital, Boston, MA. Ue report that a ,~]broblast produced factor can ollow the .~rolon~,ed survival oF activated IL-2 propagnt,bl T lybphocFtes in tI~,~ nbseT~, o ~ IT,-2 or antigenic stimulation. Uhen the activated ceils are remove4 from the presence of aatigen{e sti;m~li oz- p r o l i f e r a t i o n - i n d u c i n z cytokines (such as [L-2), they rapi,!] F cease ,',ividing and succu-~.h to apoptosis. .~owever, IT.-2 lep:~'n.].-
r e t a i n e d , and s u r v i v i n ' ~ c a l ] s r a a a i u e d s ) e c i f i c e v t o t o x i e a c t i v i t y . The r e s p o n s i b l e f a c t o r s have n o t v e t b e e n ] c ~ a n t i f i e d , b u t t ~ e a c t i v i t y of the FC~I is distinct £ron any o ~ the [nt,r]eukins I throulh 7. These results su<~cs~ an antigen non sr)<~cific ",mchn~{s t f(~r retention of activated "memory "~ lwphocyt~,s. The f[broblast source o~ this activity su:
AN IMMUNOCHEMICAL EXPLANATION FOR THE CYNAP PHENOMENON AND FOR ANTIHUMAN KAPPA Ig (AHG) AUGMENTED CYTOTOXICITY (CDC). T.C.Fuller,A.Fuller,M.Golden,S.Zakroff and G.E.Rodey. Mass. Gen. Hospital, Boston MA. and Emery University, Atlanta GA. HLA Class I alloantigens express multiple epitopes and human alloantibodies (aAb) have been identified against many of them. We have shown that individual aAb are nonreactive in standard CDC (CYNAP) but can be converted to direct C D C with the addition of AHG to C D C (Transplantation 34:24, 1982). The mechanisms for this phenomena have now been clarified by experiments using affinity-purified aAb, subclass specific @IgH, human Clq binding assays using an indirect sandwich assay and quantitation by flow cytometry. We have found that CYNAP reactions are not generally caused by low affinity or non-C fixing aAb [evidence: Fab and F(ab')2 HLA aAb are not augmented in AHG-CDC nor are antiIgH chain reagents effective with aAb; in fact, @-IgG(Fc) inhibits C D C due probably to steric blockage of C binding]. Use of single HLA aAb populations in conjunction with the AHG(kappa)-augmenting reagent results in a 200% to 400% increase in Clq binding over that when either reagent is used alone, thus demonstrating synergy of the reactants. These experiments indicate that two adjacent, noncompeting HLA aAb bound to spatially distinct epitopes on an HLA molecule, or a single HLA specific aAb in concert with the AHG binding to this HLA aAb, are required for efficient (bivalent) Clq binding and C-mediated lympholysis. In contrast, CYNAP is caused by the presence of a single population of aAb which cannot fix Clq bivalently and thus, cannot induce the subsequent cascade of C components.