Three monoclonal antibodies against human LFA-1 alpha and beta chains with different biological activities.

Three murine monoclonal antibodies (MAbs) directed against human lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18), designated as MAY.017, MAY.035, and MAY. 044, were newly generated. The hybridomas were screened for their ability to inhibit a phorbol ester-stimulated aggregation of Epstein-Barr virus-transformed B-lymphoblastoid cell line (B-LCL). The MAbs bound to peripheral blood leukocytes, T cell lines, B cell lines, and some of myeloid/monocytic lines, but not to B-LCL derived from a patient with leukocyte adhesion deficiency. MAY.035 immunoprecipitated a complex of proteins with molecular masses of 155 kDa and 95 kDa, while MAY.017 and MAY.044 did a complex of 130 kDa, 155 kDa and 95 kDa proteins. MAY.035 was shown as to recognize the alpha chain of LFA-1 (CD11a), and both MAY.017 and MAY.044 the beta chain of the beta 2 integrin family (CD18). All the three MAbs inhibited lymphocyte proliferative responses to mitogens or alloantigens. MAY.017 blocked cytolytic activity mediated by natural killer cells.