A new test for phagocytosis of human alveolar macrophages in suspension, using 99mTc labelled human serum albumin particles.

Current studies on human alveolar macrophages (HAM phi) indicate that two subpopulations may exist: adherent and nonadherent HAM phi. Most works in the literature were done exclusively on adherent HAM phi. In order to obviate to the loss of nonadherent HAM phi, we elaborated a new test for measuring endocytosis in HAM phi suspensions. According to this method, HAM phi in suspension were allowed to phagocytize millimicrospheres of human serum albumin labelled with 99m Tc (0.2 less than 0 less than 0.5 m; TcK9R - Cis Sorin Biomedica). Bound activity was separated from free activity by centrifugation on PercollR. The resulting internatant ring was found to contain activity bound to HAM phi which had phagocytized human serum albumin millimicrospheres. HAM phi were characterized by morphology and cytochemistry. The method here presented allows the functional study of both adherent and non-adherent HAM phi populations.