<prompt> Which of the following cell surface markers is required for lysis of IgG-coated target cells antibody-dependent, cell-mediated cytotoxicity, or ADCC by natural killer cells?CD3CD16CD19CD21  <response>: CD16 is a cell surface marker used to identify natural killer NK cells lymphocytes lacking most T- and B-cell markers. CD16 is an Fc receptor for IgG, allowing the NK cells to bind to the coated target cell during ADCC, facilitating lysis. Also know: CD3 is a five-polypeptide cluster that represents the non-variable pa of the T-cell receptor complex. The variable pa is able to rearrange itself to adapt to specific antigens. Natural killer cells are CD3-negative. CD19 is a B-cell marker. It is a signal-transducing molecule that is expressed in early B-cell differentiation. NK cells are negative for CD19. C21 is also a B-cell marker. It is a complement receptor, and is also the same receptor the Epstein-Barr virus uses to bind to cells during infection. Ref: Levinson W. 2012. Chapter 58. Cellular Basis of the Immune Response. In W. Levinson Ed, Review of Medical Microbiology Immunology, 12e. 