CD79a and CD79b form a heterodimer molecular complex. Together with the membrane surface immunoglobulin of B cells, they form the antigen recognition receptor of B cells, participate in the signal transduction of B cell activation, and can be a broad-spectrum marker of B cells. They can be labeled from the former B cells to mature plasma cells. Because the expression of CD79a decreased during terminal differentiation, the staining may be due to the cross reaction of CD79b. It is often used in combination with other antibodies for the diagnosis of B-cell lymphoma.