The detection of alloantibodies to subpopulations of human lymphocytes: an adaptation of the indirect anti-immunoglobulin rosetting reaction (IARR).

An indirect anti-immunoglobulin rosetting reaction (IARR) can be successfully used to detect alloantibodies to human lymphocytes. In this paper we describe an adaptation of the IARR which allows detection of alloantibodies to human lymphocyte subpopulations. Fluorescein labelled sheep red cells, as a T cell marker, are incorporated into the rosetting reactions and by looking for rosettes with two indicator cell types, sheep and ox, one can determine if the alloantibodies are reacting with T cells or non-T cells. This type of assay is more sensitive than a standard cytotoxic test and can detect non-cytotoxic antibodies. The results show that this rosetting assay with two types of indicator cell can be useful in the study of pregnancy anisera, particularly those that are thought to contain reactivity directed solely against non-T cells. These antisera probably recognise the human DR antigens which are thought to be equivalent to the rodent Ia antigens.