Soluble CD4: a link between specific immune mechanisms and non-specific inflammatory responses?

The CD4 molecule is an important cell surface molecule expressed on many cell types including T-helper cells. CD4 can be shed from cells, and the truncated soluble form of CD4 (sCD4) has been found elevated in serum in several diseases. In this study the authors show that migration of polymorphonuclear neutrophils (PMN) is induced by sCD4. Histopathology of the site of injection of recombinant sCD4 in the skin shows local infiltration of PMN. In vitro, in Boyden chamber, sCD4 can rapidly give rise to a dose-dependent migration of PMN. The authors speculate that sCD4 can be another chemotactic factor and, as such, constitutes a link within the immune system between specific and non-specific elements of inflammation.