Medical Health Encyclopedia

Cytokines and the Inflammatory Response. TH cells also secrete or stimulate the production of powerful immune factors called cytokines. In small amounts, cytokines are indispensable for healing. If overproduced, however, they can cause serious damage, including inflammation and injury during the scleroderma process.

A cytokine known as connective transforming growth factor (CTGF) appears to be particularly important. It acts in concert with another compound called TGF-beta to stimulate the growth of fibroblasts. Fibroblasts are immature cells that regulate production of collagen. Collagen is the tough protein used to build the fibrous structures that form bones, ligaments, and skin. It is also the basic building block in scar tissue, a major component in scleroderma.

Other cytokines that may have major roles in scleroderma include tumor necrosis factor and interleukins.

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Neutrophils. Cytokines attract to the scene large numbers of other white blood cells known as neutrophils. Neutrophils stimulate the production of arachidonic acid, which triggers about 30 different chemicals, including leukotrienes. Specific leukotrienes called LTB(4) and LTE(4) are elevated in scleroderma patients and may contribute specifically to lung disease.

Fetal Cell Theory and Microchimerism

Increasing evidence supports a cause of scleroderma called microchimerism. It arose from the observation that scleroderma occurs in mostly women and that its symptoms resembled those of graft-versus-host disease (GVHD). GVHD occurs in bone transplant patients when the transplanted donor cells launch an attack against the host-patient's cells.

To understand the process, it is useful to define chimerism, which occurs when cells from two different individuals exist in the same body. When there is a low number of cells of one body in another, the condition is referred to as microchimerism.