Phylogeny of lymphocyte heterogeneity. I. Membrane immunoglobulins of teleost lymphocytes.

Immunofluorescence studies of bream lymphoid tissues revealed that our 90% of the lymphocytes from blood, anterior kidney, spleen and thymus exhibited membrane immunoglobulin determinants. Furthermore, a majority of such cells were observed to undergo patching and capping when the membrane proteins were complexed with antisera to fish serum immunoglobulins. Lactoperoxidase catalysed radioiodination, detergent lysis and immunoprecipitation with appropriate antisera were employed to study the properties of this membrane immunoglobulin. Quantification, by inhibition of immunoprecipitation with serum immunoglobulin, indicated the average amount of immunoglobulin determinants for bream lymphocytes from either blood, anterior kidney, spleen or thymus to be about half that present on mouse B cells. Physiochemical characterization of labeled membrane immunoglobulin from bream lymphocytes suggested that only one class of immunoglobulin heavy chain was present and that about one-half of this material resembled the monomeric (2H-2L chain) IgM-like proteins present in bream serum. A major unanswered question raised by this study was whether or not certain of the bream membrane immunoglobulin determinants were associated with molecules that did not resemble "classical" immunoglobulins.