High incidence of group C streptococci isolated from throat swabs.

Value of factor VII reated atigen a means of demnstratig extmeduar haemopofresWe have noted the comments of Dr AL Bloom and Dr JC Giddings' concerning our use of the localisation of factor VIII related antigen (F VIII RAg) in platelets and megakaryocytes.2These are, indeed, valid points and it is accepted that conta- minants such as fibronectin may be responsible for weak activity of their cor- responding antibodies in commercial anti- sera.It should be appreciated, however, that the staining obtained with such prep- arations is not only intense but appears to be found specifically in megakaryocytes and vascular endothelium.3Moreover, his- tiocytes, which contain, for example, fibronectin, are not, in our hands, stained