A New Rare Blood Group Antigen To^a (Torkildsen) and an Unsolved Factor Skjelbred

Abstract

A previously unrecognized, rare blood group antigen, To^a (Torkildsen), and a rare, so far unsolved erythrocyte factor, Skjelbred, have been described. The To^a antigen seems to be inherited as a Mendelian dominant character. Sera containing anti-To^a and anti-Skjelbred, showing the characteristics of ‘naturally occurring’ antibodies, are relatively frequently found.

Skjelbred, a Low Frequency Antigen in Serum and on Red Cells

“…Investi gation of this and other similar problems from an American Laboratory led to the identification of the antigen involved as be ing the same as Skjelbred, described by Kornstad et al [1] in 1968. A preliminary report of this collaborative work was pre sented by Kornstad et al [2] in 1977; a detailed report of the investigation in the United Kingdom is given below.…”

“…The original account of Kornstad et al [1] reported the 'factor' to be detectable only once in screening red cells of over 12,000 Norwegian donors. Now 8 and, if Mr. W. is included, possibly 9 have been detected in the United Kingdom, and 2 cases detected in America [2].…”

“…When cells of this donor were referred to Dr. L. Kornstad (Oslo), they were identified as Skjelbred-positive(Sk(+)), the first since it was reported in 1968 [1], Testing of Mr. R.'s cells in London and Oslo also confirmed that they were Sk(+). Absorption and elution experiments showed that the English and American Sk(+) cell samples were both reacting with the same anti body as the cells of Mr. Skjelbred [2], The expres sion of Sk varied in strength; cells of RjRj-85 were markedly weaker than those of Mr. R. [2].…”

“…Cells of the original propositus, Mr. Skjelbred [1], had been tested on a fairly regular basis and shown to be still active in January 1976, but when a fresh blood sample was obtained in February 1977, the antigen was no longer present. Again the antigen was never clearly demonstrated in his serum.…”

“…The Skjelbred antigen (Sk) was originally reported as an unsolved factor [1] since the family study of the propositus did not reveal any other members with an expression of the antigen. The discovery that the antigen…”