Immunoglobulin, complement, and histocompatibility antigen studies in keloid patients.

The increased collagen synthesis and deposition, which is characteristic of keloids, may be related to an immune response initiated by wounding. Therefore, we examined various systemic and localized immune parameters in keloid patients to establish if such factors are related to keloid pathogenesis. To determine if there is a systemic immune response, we compared the serum levels of IgG and IgM in keloid patients to those in a closely matched population. In addition, we measured complement levels (Clq, C3, and C4) and receptors for sheep (E), mouse erythrocytes (MRBC), and complement (EAC) on blood lymphocytes. All of these were in the normal range in the keloid patients. However, the extractable IgG from keloid tissue was significantly increased (compared to normal skin and normal scar controls), suggesting a localized immune response. To determine whether keloid formation is associated with a specific histocompatibility locus, human lymphocyte antigen (HLA) profiles of 45 keloid patients were analyzed; no significant differences in the incidence of HLA-A and B antigens were found (compared to 200 controls). These studies suggest that there is a localized immune response involved in keloid pathogenesis, one which is not related to either the HLA-A or B histocompatibility loci.