Genetic and serologic re-evaluation of LyM-1 antigen specified by a gene closely linked to Mls: establishment of LyM-1 antigen of the mouse.

An alloantiserum prepared against LyM-1 antigen of the mouse has been analysed in detail. This antiserum, C3H/HeJ anti-CBA/J, has turned out to define two antigens which are specified by independently segregating loci. One of these is Lyb-2.1 or similar antigen specified by a gene located on chromosome 4. The other is identified as LyM-1.2 based on the result that a gene determining alloantigenicity in the Lyb-2- strain is closely linked to Mls with recombination frequency of 0.066 +/- 0.028. Since both antigens are expressed preferentially on B lymphocytes and their strain distribution is significantly overlapped, there has been much confusion about LyM-1 antigen. This is overcome by re-evaluating anti-LyM-1.2 serum under the condition in which Lyb-2.1 is not involved in analysis. The strain distribution of LyM-1 antigen, its preferential expression on B lymphocytes and close genetic linkage of LyM-1 to Mls have been established.