Pseudothrombocytopenia may have any of a number of causes, one of which is agglutination in vitro. This phenomenon was found in samples of blood from six patients. A serum factor responsible for the agglutination was demonstrated. The factor was dependent upon the presence of EDTA and was more active at room temperature than at 37 C. It could be identified as an IgM immunoglobulin in four cases. In the other two cases definite characterization was not possible, but there was some evidence in favor of an IgM factor. All six patients had elevated serum IgM levels, but they had different and unrelated clinical disorders.

A group of 40 patients with idiopathic thrombocytopenic purpura (ITP) was examined. Typing for HLA A and B antigens was performed. The frequencies of 24 HLA antigens in this group were compared with those of a group of 13 patients with drug-induced thrombocytopenia and two large groups of healthy controls. Differences of statistical significance between these groups were not found. Thus, associations of ITP and particular HLA antigens were not observed. The associations reported by others could not be confirmed.

A case of Werlhof's disease (immune thrombocytopenia) associated with myasthenia gravis is described. The two disorders developed within a few months of each other. The immunological and practical aspects of the association are discussed.

ABSTRACT. A case of idiopathic acquired pan‐myelopathy (aplastic anaemia) in pregnancy in a 32‐year‐old woman is presented. The outcome for mother and child was favourable. Special attention is paid to the management of the delivery. Another aspect of interest is the haematologic status of the child. In panmyelopathy an immunologic mechanism may operate as indicated by the finding of platelet membrane associated immunoglobulins, which were also present in our patient. If the bone marrow lesions in this disease are indeed due to immunological injury, they are mediated by immune complexes or by a cellular mechanism, for it is well known that IgG antibodies may pass through the placenta and induce lysis of circulating blood cells in the newborn. There was no evidence of bone marrow damage in the infant. This is in accordance with the cases mentioned in the literature.