Recognition of CD52 allelic gene products by CAMPATH-1H antibodies

Cloning of the CD52 from a B-lymphocyte tumour cDNA library revealed two closely related sequences differing only at two amino acids C-terminal to the proposed point of glycosylphosphatidylinositol (GPI)-linkage. When transfected into CHO cells only one of these sequences gave high-level expression of the antigen recognized by the prototypic anti-CD52 antibody CAMPATH-1 whereas in JURKAT cells good expression levels were obtained with both sequences. Fusion of the sequence from the second sequence to DNA encoding the extracellular domain of CD4 indicated that this sequence was capable of directing GPI linkage. The possible implications for the function of CD52 and serotherapy with anti-CD52 antibodies are discussed.