IGM AUTOANTIBODIES TO 180-KD AND 230-KD TO 240-KD HUMAN EPIDERMAL PROTEINS IN PREGNANCY

Background and Design: A previous study has suggested that there is a novel entity among the polymorphous eruptions of pregnancy (PEP) assoc iated with circulating anti-basement membrane zone IgM autoantibodies. To determine if the presence of antibasement membrane zone IgM autoan tibodies is a feature of PEP, serum samples from 52 patients with a PE P, 69 healthy pregnant women, and 42 nonpregnant women were prospectiv ely evaluated by indirect immunofluorescence using salt-split human sk in as substrate. Serum samples were also tested by immunoblotting usin g keratinocyte extracts and anti-human IgM antibodies. The reactivity of some serum samples was examined using two recombinant bullous pemph igoid antigen proteins. Results: The percentage of women with a PEP, h ealthy pregnant women, and nonpregnant women who had antibasement memb rane zone IgM antibodies by indirect immunofluorescence was similar: 1 2%, 10%, and 14% of cases, respectively. By immunoblotting, 14% of the serum samples from the patients with a PEP, 12% of the serum samples from the healthy pregnant women, but only 2% of the serum samples from the nonpregnant women contained IgM antibodies that reacted with epid ermal proteins of 180 and/or 230 to 240 kd. The recombinant bullous pe mphigoid antigen proteins were not recognized by any of the serum samp les that showed a reactivity by immunoblotting using keratinocyte extr acts. Conclusion: There is no evidence for the existence of a novel en tity of pregnancy defined by circulating antibasement membrane zone Ig M autoantibodies. Immunoblotting detects IgM autoantibodies that react with epidermal proteins of 180 and/or 230 to 240 kd. These autoantibo dies appear to be more frequent in pregnant than in nonpregnant women. Although the nature of the target antigen(s) remains to be establishe d, pregnancy may be associated with low levels of IgM autoreactivity a gainst epidermal proteins.