Dissemination of mycobacteria to other organs
Dissemination of mycobacteria from the lung to other organs can occur when macrophages become infected with bacteria following phagocytosis. Migration of activated macrophages to secondary lymphoid tissue for antigen presentation to CD4+ helper T lymphocytes can spread the bacteria to other tissues such as liver, lymph nodes, spleen, gut and bone marrow.
Dissemination of mycobacteria to the spleen
Arterial blood flows into the spleen and comes into contact with lymphoid tissue known as the white pulp which is rich in lymphocytes and antigen-presenting cells. Foreign antigen is detected here and inflammatory responses are initiated. Macrophages infected with mycobacteria may enter the spleen and spread bacteria to other macrophages.