Further characterization of human myeloid antigens (gp160,95; gp150; gp67): investigation of epitopic heterogeneity and non-haemopoietic distribution using panels of monoclonal antibodies belonging to CD-11b, CD-13 and CD-33.
We have investigated the binding of over 30 different monoclonal antibodies (MAB) belonging to three distinct clusters of differentiation (CD-11b; CD-13; CD-33; as defined by the Third International Workshop on Leucocyte Differentiation Antigens (ILWS), 1986), and which are reactive with three distinct myeloid restricted surface antigens ('gp160,95'; 'gp150'; 'gp67'). By investigating reactivity with non-haemopoietic cells, we have confirmed that CD-11b and CD-33 MAB reactivity is largely restricted to haemopoietic cells, whilst CD-13 MAB showed additional binding to a wide range of non-haemopoietic cells. Epitopic heterogeneity was also investigated within each cluster of differentiation. Tested anti-CR3 (CD-11b) MAB varied in their ability to block the binding of complement coated sheep red blood cells and zymosan particles. A more detailed analysis of MAB binding heterogeneity was performed by competitive inhibition assays. It was demonstrated that MAB from both CD-11b and CD-13 bind to several distinct epitopes (at least six and five respectively) on their respective antigen molecules. In contrast, CD-33 MAB appear to bind to only a single site on 'gp67'. These data may allow for a clearer appreciation of the disparate functional effects obtained using different MAB reagents to individual myeloid antigens, as reported by a number of workers.
Favaloro
E J
EJ
Department of Haematology, ICPMR, Westmead Hospital, NSW, Australia.
Bradstock
K F
KF
Kabral
A
A
Grimsley
P
P
Zowtyj
H
H
Zola
H
H
D000911:Antibodies, Monoclonal; D001667:Binding, Competitive; D001853:Bone Marrow / Q000276:immunology; D000939:Epitopes / Q000032:analysis*; D006801:Humans; D016256:Lewis X Antigen / Q000032:analysis*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D016256:Lewis X Antigen