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Morphological and functional characteristics of subpopulations of amoebocytes in the snail Lymnaea Stangalis: Effect of infection with Trichobilharzia ocellata
Vol.
I0, No.'l
IMMUNOPARASITOLOGY
139
MORPHOLOGICAL AND FUNCTIONAL CHARACTERISTICS OF SUBPOPULATIONS OF AMOEBOCYTES IN THE SNAIL LYMNAEA STAGNALIS: EFFECT OF INFECTION WITH TRICHOBILHARZIA OOEL-
LATA. Wil van der Knaap, Ronald Dikkeboom, Willy Bogers and Jolanda Tijnagel. Lab. Med. Parasitol., Free University, P.O.Box 7161, Amsterdam, The Netherlands. The haemocytes (amoebocytes) of the pond snail Lymnaea stagnalis constitute a morphologically and functionally heterogeneous population. Due to the oresence of the schistosome Trichobilharzia ocellata, developing in the snail, the number of circulating haemocytes increases strongly; large haemocytes appear which have the morphological characteristics of highly differentiated cells, but a decreased phagocytic avidity. The hypothesis was tested that the alterations in number, morphology and phagocytic avidity are brought about by the decrement in size of certain subpopulations of haemocytes and the incremant of other subpopulations. A monoclonal antibody (Moab) which recognizes preferentially immature haemocytes of juvenile snails was used to stain, immunocytochemically, monolayers of haemocytes from adult uninfected snails and from adult snails carrying patent infections of T. ocel~ata. Also, monolayers were stained of which the haemocytes had had the opportunity to phagocytose sheep red blood cells or had been reacted for endogeneous peroxidase. The proportion of Moab+ cells was decreased in infected snails; both the Moab- and Moab+ cells looked more differentiated and had a higher content of endogeneous peroxidase than those of uninfected snails. The phagocytic avidity of Moab- cells was decreased; whether or not the Moab+ cells had a decreased phagocytic avidity could not be demonstrated. It is concluded that - if shifts in the size of certain subpopulations are responsable for the alterations in the haemocyte system - Moabs should be used which differ entiate between the subpopulations that make up the now Moab- subpopulation.
MORPHOLOGICAL AND FUNCTIONAL CHARACTERISTICS OF A MONOCLONAL ANTIBODY RECOGNIZED SUBPOPULATION OF AMOEBOCYTES OF JUVENILE AND ADULT LYMNAEA STJGNALIS. Ronald Dikkeboom, Wil van der Knaap, Willy Bogers and Jolanda Tijnage!. Lab. Med. Parasitology, Free University, Amsterdam, The Netherlands. Juvenile and adult Lymnaea stagnalis both have a heterogeneous population of haemocytes (amoebocytes). Morphologically immature cells with low immunocompetence dominate the haemogram of juvenile snails, whereas in adults large numbers of mature, highly immunocompetent cells prevail. The immature haemogram of juvenile snails could be a cause of their relatively high susceptibility to the schistosome parasite Trichobilharzia ocellata. In the present study this inter- and intra-snail heterogeneity is further characterized by using monoclonal antibodies. A monoclonal antibody (moAb LSI), raised against haemocytes of adult snails, recognizes an antigenically distinct subpopulation in both juvenile and adult snails. Lightmicroscopically the LSI+ cells are small, less differentiated haemocytes. They have a lower phagocytic capacity and contain hardly ever endogeneous peroxidase, in contrast to LSI- haemocytes. As adult snails contain less LSI+ haemocytes (14%) than juveniles (39%) it is suggested that the LSI+ cells loose the LSI epitope during their maturation.
I0, No.'l
IMMUNOPARASITOLOGY
139
MORPHOLOGICAL AND FUNCTIONAL CHARACTERISTICS OF SUBPOPULATIONS OF AMOEBOCYTES IN THE SNAIL LYMNAEA STAGNALIS: EFFECT OF INFECTION WITH TRICHOBILHARZIA OOEL-
LATA. Wil van der Knaap, Ronald Dikkeboom, Willy Bogers and Jolanda Tijnagel. Lab. Med. Parasitol., Free University, P.O.Box 7161, Amsterdam, The Netherlands. The haemocytes (amoebocytes) of the pond snail Lymnaea stagnalis constitute a morphologically and functionally heterogeneous population. Due to the oresence of the schistosome Trichobilharzia ocellata, developing in the snail, the number of circulating haemocytes increases strongly; large haemocytes appear which have the morphological characteristics of highly differentiated cells, but a decreased phagocytic avidity. The hypothesis was tested that the alterations in number, morphology and phagocytic avidity are brought about by the decrement in size of certain subpopulations of haemocytes and the incremant of other subpopulations. A monoclonal antibody (Moab) which recognizes preferentially immature haemocytes of juvenile snails was used to stain, immunocytochemically, monolayers of haemocytes from adult uninfected snails and from adult snails carrying patent infections of T. ocel~ata. Also, monolayers were stained of which the haemocytes had had the opportunity to phagocytose sheep red blood cells or had been reacted for endogeneous peroxidase. The proportion of Moab+ cells was decreased in infected snails; both the Moab- and Moab+ cells looked more differentiated and had a higher content of endogeneous peroxidase than those of uninfected snails. The phagocytic avidity of Moab- cells was decreased; whether or not the Moab+ cells had a decreased phagocytic avidity could not be demonstrated. It is concluded that - if shifts in the size of certain subpopulations are responsable for the alterations in the haemocyte system - Moabs should be used which differ entiate between the subpopulations that make up the now Moab- subpopulation.
MORPHOLOGICAL AND FUNCTIONAL CHARACTERISTICS OF A MONOCLONAL ANTIBODY RECOGNIZED SUBPOPULATION OF AMOEBOCYTES OF JUVENILE AND ADULT LYMNAEA STJGNALIS. Ronald Dikkeboom, Wil van der Knaap, Willy Bogers and Jolanda Tijnage!. Lab. Med. Parasitology, Free University, Amsterdam, The Netherlands. Juvenile and adult Lymnaea stagnalis both have a heterogeneous population of haemocytes (amoebocytes). Morphologically immature cells with low immunocompetence dominate the haemogram of juvenile snails, whereas in adults large numbers of mature, highly immunocompetent cells prevail. The immature haemogram of juvenile snails could be a cause of their relatively high susceptibility to the schistosome parasite Trichobilharzia ocellata. In the present study this inter- and intra-snail heterogeneity is further characterized by using monoclonal antibodies. A monoclonal antibody (moAb LSI), raised against haemocytes of adult snails, recognizes an antigenically distinct subpopulation in both juvenile and adult snails. Lightmicroscopically the LSI+ cells are small, less differentiated haemocytes. They have a lower phagocytic capacity and contain hardly ever endogeneous peroxidase, in contrast to LSI- haemocytes. As adult snails contain less LSI+ haemocytes (14%) than juveniles (39%) it is suggested that the LSI+ cells loose the LSI epitope during their maturation.