ORGANS OF IMMUNE SYSTEM

Primary lymphoid organs
Bone marrow
Thymus

Lymphatic System
Secondary Lymphoid Organs
Lymph node
Spleen
Mucosal-associated lymphoid tissue (MALT) 
Cutaneous-associated lymphoid tissue (CALT)

Primary lymphoid organs: 

The primary lymphoid organs include the bone marrow and thymus. As you already know these are the organs where the cells of the immune system originate and mature.