IN-VIVO TISSUE DISTRIBUTION OF CD4 LYMPHOCYTES IN MICE DETERMINED BY RADIOIMMUNOSCINTIGRAPHY WITH AN IN-111-LABELED ANTI-CD4 MONOCLONAL-ANTIBODY

The tissue distribution of CD4 lymphocytes in normal C57/BL mice and C D4 knockout mice was determined by biodistribution measurements and ga mma camera imaging with an In-111-labeled rat IgG(2b) monoclonal antib ody directed against the murine CD-4 antigen. In normal mice, high con centrations of antibody accumulated in the spleen and lymph nodes, at 45 hr after injection, the concentrations of radiolabel in the spleen and lymph nodes of normal mice were 10- to 20-fold greater than in the corresponding tissues of the CD4 knockout mice and nonlymphoid tissue s of both types of mice. At 24 and 45 hr, gamma camera images showed h igh concentrations of radiolabeled antibody in lymph nodes and spleen of normal but not knockout mice. These results indicate that radioimmu noscintigraphy with In-111-anti-CD4 is an excellent method for studyin g tissue distribution of CD4 lymphocytes in mice, Using an equivalent anti-human CD4 antibody, this method might be useful for studying the pathophysiology of conditions in which these cells play a critical rol e and for monitoring therapies for these disorders.