Macrophages and T-Lymphocytes Secrete Collagen

There are several potential sources of origin for the capsule collagen that surrounds a dormant or benign tumor that is not a pseudo-capsule generated from compression of the stromal tissues.  One overlooked source of the capsule demonstrated by Vaage in 1991 is the immune system itself, with lymphocytes and macrophages surrounding aberrant, immunogenic cells with a collagen capsule.  Research regarding the involvement of macrophages and lymphocytes in useful and pathological collagenous fibrosis is an important facet of fibrosis mechanisms that is still highly relevant today, in 2012.  Of course, any collagen synthesis requires Vitamin C/ascorbic acid/ascorbate.  Innate defense and cytotoxic immune cells in particular use vastly large quantities of it, accumulating it against an osmotic gradient to 100-fold more than the surrounding serum or plasma.

Collagen production by macrophages in tumour encapsulation and dormancy.

Fibrous Capsule of a dormant (not growing) tumor (Vaage 1991)

T-Lymphocyte Secreted Collagen Fibers, Vaage 1991

 

 

Collagen Tumor Capsules Break Open in Metastasis

There have been constant redefinitions of schirrhous response or the desmoplastic response in which the body encapsulates a tumor with collagen. Some would say that this was a negative prognostic, others that it was a good one. Certainly science has been confused as to the importance of "walling off" a tumor with collagen. It is not an imaginary computer graphics simulation, but a real phenomenon that is a biochemical reflex to turn an irritating mass into a benign one.

When metastasis occurs, these collagen capsules are broken open and the malignant cells spill outside, free to invade other tissues or the blood circulation. Clearly, the visual evidence suggests that the desmoplastic response is important to create a mechanical barrier, a wall, beyond which malignant tumor cells cannot pass. When these cells breach the wall, they have effectively begun to metastasize.

Tumor cell budding from focally disrupted tumor capsules: a common pathway for all breast cancer subtype derived invasion?